SEPTEMBER 17, 2026
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Case File

CVE-2026-73309

HIGH · CVSS 7.4 EPSS 0.48% Public Exploit

Source: NVD + CISA KEV + EPSS · Published 2026-09-08 · Last synced 2026-09-17

CyberRota Analysis

AI-Generated

XenForo versions prior to 2.3.13 are vulnerable to an authentication bypass in the OAuth2 token endpoint, allowing unauthenticated attackers to obtain valid token pairs by exploiting PHP truthy evaluation logic. This vulnerability enables attackers to bypass client secret and PKCE code verifier validation, compromising user authentication and potentially leading to unauthorized access. Organizations using affected XenForo versions should prioritize patching to mitigate the risk of exploitation.

Public Exploit Signal

A public exploit, PoC, GitHub repository or Metasploit reference was detected for this CVE.

Detected Signals
exploit
GitHub PoC Links

Note: these links are listed for security research and verification purposes only.

CVE
CVE-2026-73309
Severity
HIGH
CVSS
7.4
EPSS
0.48%
Exchange

Original NVD Description

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.

Related CVEs

Other vulnerabilities affecting the same vendor(s)