9.1

CVE-2026-73309

Exploit

XenForo < 2.3.13 Authentication Bypass via OAuth2 Token Endpoint

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.
Daten sind bereitgestellt durch National Vulnerability Database (NVD)
Xenforo ≫ Xenforo Version < 2.3.13
VulnDex Vulnerability Enrichment
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Zu dieser CVE wurde keine Warnung gefunden.
EPSS Metriken
Typ Quelle Score Percentile
EPSS FIRST.org 0.47% 0.392
CVSS Metriken
Quelle Base Score Exploit Score Impact Score Vector String
NIST 9.1 3.9 5.2
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
disclosure@vulncheck.com 9.1 0 0
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
disclosure@vulncheck.com 7.4 2.2 5.2
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
CWE-697 Incorrect Comparison

The product compares two entities in a security-relevant context, but the comparison is incorrect.

https://xenforo.com/community/threads/security-fixes-released-for-all-xenforo-and-media-gallery-versions-2-2-0-2-3-12.239856/
Release Notes
https://xenforo.com/community/threads/xenforo-2-3-13-and-add-ons-released-includes-security-fixes.239857/
Release Notes
https://www.vulncheck.com/advisories/xenforo-authentication-bypass-via-oauth2-token-endpoint
Third Party Advisory
https://bombobombone.github.io/posts/cve-2026-73309/
Third Party Advisory
Exploit
https://github.com/BomboBombone/CVE-2026-73309
Third Party Advisory