CVE-2026-103276: Software Security Vulnerability Vulnerability

MODERATE
Advisory Identifier: GHSA-v575-g66p-vj84
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CVSS 5.3
CWE-173
Published
Advisory Summary

CVE-2026-103276 is a MODERATE (CVSS 5.3) security vulnerability vulnerability (CWE-173: Improper Handling of Alternate Encoding) affecting Software libraries in the Maven ecosystem. The weakness occurs when the product does not properly handle when an input uses an alternate encoding that is valid for the control sphere to which the input is being sent.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-103276 at a Glance

CVE Identifier CVE-2026-103276
GHSA Identifier GHSA-v575-g66p-vj84
Severity MODERATE
CVSS v3.1 Base Score 5.3
CWE Classification CWE-173: Improper Handling of Alternate Encoding
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 5.3

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:L/I:N/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 Low (C:L)
Integrity None (I:N)
Availability None (A:N)

How to Fix CVE-2026-103276

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

Verify Direct and Transitive Dependencies

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

mvn dependency:tree

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2026-103276, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree

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

Note: The mvn dependency:tree command inspects the resolved dependency graph declared in your project's POM files; it does not perform automated security scanning or inspect runtime dynamic classpaths. Always verify runtime container classpaths and shaded JARs.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-173: Improper Handling of Alternate Encoding, where the product does not properly handle when an input uses an alternate encoding that is valid for the control sphere to which the input is being sent. In Software, 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

Ghost versions before 6.20.0 contain a file extension filtering bypass vulnerability that allows unauthenticated attackers to read theme templates and metadata. Attackers can use URL encoding to bypass extension validation and access sensitive theme files.

References

GitHub Advisory / Wiki ADVISORY
https://github.com/TryGhost/Ghost/security/advisories/GHSA-6v8p-3jx9-8chr
NVD — CVE-2026-103276 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-103276
www.vulncheck.com/advisories/ghost-be... WEB
https://www.vulncheck.com/advisories/ghost-before-6.20.0-file-read-via-url-encoding-bypass

Frequently Asked Questions

What is CVE-2026-103276?
CVE-2026-103276 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-173: Improper Handling of Alternate Encoding.
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-103276?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What is the CVSS score of CVE-2026-103276?
CVE-2026-103276 has a CVSS v3.1 base score of 5.3 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N.
What CWE is associated with CVE-2026-103276?
CVE-2026-103276 is classified under CWE-173: Improper Handling of Alternate Encoding (The product does not properly handle when an input uses an alternate encoding that is valid for the control sphere to which the input is being sent.).
How can I check Maven dependencies for CVE-2026-103276?
Run the dependency tree command: 'mvn dependency:tree'. 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-v575-g66p-vj84",
  "modified" : "2026-10-01T12:31:18Z",
  "published" : "2026-10-01T12:31:18Z",
  "aliases" : [ "CVE-2026-103276" ],
  "details" : "Ghost versions before 6.20.0 contain a file extension filtering bypass vulnerability that allows unauthenticated attackers to read theme templates and metadata. Attackers can use URL encoding to bypass extension validation and access sensitive theme files.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X"
  } ],
  "affected" : [ ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/TryGhost/Ghost/security/advisories/GHSA-6v8p-3jx9-8chr"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-103276"
  }, {
    "type" : "WEB",
    "url" : "https://www.vulncheck.com/advisories/ghost-before-6.20.0-file-read-via-url-encoding-bypass"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-173" ],
    "severity" : "MODERATE",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-10-01T11:17:23Z"
  }
}