CVE-2026-73309: Software Security Vulnerability Vulnerability

CRITICAL
Advisory Identifier: GHSA-pr5w-fh2v-7c9q
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CVSS 7.4
CWE-697
Published
Advisory Summary

CVE-2026-73309 is a CRITICAL (CVSS 7.4) security vulnerability vulnerability (CWE-697: Incorrect Comparison) affecting Software libraries in the Maven ecosystem. The weakness occurs when the product compares two entities in a security-relevant context, but the comparison is incorrect.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-73309 at a Glance

CVE Identifier CVE-2026-73309
GHSA Identifier GHSA-pr5w-fh2v-7c9q
Severity CRITICAL
CVSS v3.1 Base Score 7.4
CWE Classification CWE-697: Incorrect Comparison
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 7.4

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N).

Attack Vector Network (AV:N)
Attack Complexity High (AC:H)
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-2026-73309

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-2026-73309, 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-697: Incorrect Comparison, where the product compares two entities in a security-relevant context, but the comparison is incorrect. 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

XenForo before 2.3.13 contains an authentication bypass vulnerability in the OAuth2 token endpoint that allows unauthenticated attackers to obtain valid token pairs by submitting empty values for client_secret and code_verifier parameters. Attackers can exploit PHP truthy evaluation logic, which treats empty strings as false and skips client secret validation and PKCE code verifier validation, to exchange a valid authorization code for a token pair without proving client identity or holding the PKCE commitment.

References

NVD — CVE-2026-73309 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-73309
bombobombone.github.io/posts/cve-2026-7330... WEB
https://bombobombone.github.io/posts/cve-2026-73309
Software Source Repository REPOSITORY
https://github.com/BomboBombone/CVE-2026-73309
www.vulncheck.com/advisories/xenforo-... WEB
https://www.vulncheck.com/advisories/xenforo-authentication-bypass-via-oauth2-token-endpoint
Software Release RELEASE
https://xenforo.com/community/threads/security-fixes-released-for-all-xenforo-and-media-gallery-versions-2-2-0-2-3-12.239856
Software Release RELEASE
https://xenforo.com/community/threads/xenforo-2-3-13-and-add-ons-released-includes-security-fixes.239857

Frequently Asked Questions

What is CVE-2026-73309?
CVE-2026-73309 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-697: Incorrect Comparison.
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-73309?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What is the CVSS score of CVE-2026-73309?
CVE-2026-73309 has a CVSS v3.1 base score of 7.4 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N.
What CWE is associated with CVE-2026-73309?
CVE-2026-73309 is classified under CWE-697: Incorrect Comparison (The product compares two entities in a security-relevant context, but the comparison is incorrect.).
How can I check Maven dependencies for CVE-2026-73309?
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-pr5w-fh2v-7c9q",
  "modified" : "2026-09-09T03:30:35Z",
  "published" : "2026-09-08T15:31:54Z",
  "aliases" : [ "CVE-2026-73309" ],
  "details" : "XenForo before 2.3.13 contains an authentication bypass vulnerability in the OAuth2 token endpoint that allows unauthenticated attackers to obtain valid token pairs by submitting empty values for client_secret and code_verifier parameters. Attackers can exploit PHP truthy evaluation logic, which treats empty strings as false and skips client secret validation and PKCE code verifier validation, to exchange a valid authorization code for a token pair without proving client identity or holding the PKCE commitment.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/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" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-73309"
  }, {
    "type" : "WEB",
    "url" : "https://bombobombone.github.io/posts/cve-2026-73309"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/BomboBombone/CVE-2026-73309"
  }, {
    "type" : "WEB",
    "url" : "https://www.vulncheck.com/advisories/xenforo-authentication-bypass-via-oauth2-token-endpoint"
  }, {
    "type" : "WEB",
    "url" : "https://xenforo.com/community/threads/security-fixes-released-for-all-xenforo-and-media-gallery-versions-2-2-0-2-3-12.239856"
  }, {
    "type" : "WEB",
    "url" : "https://xenforo.com/community/threads/xenforo-2-3-13-and-add-ons-released-includes-security-fixes.239857"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-697" ],
    "severity" : "CRITICAL",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-09-08T14:17:24Z"
  }
}