CVE-2026-73309
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.
Açıklama ve Etki
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.
Referanslar
- https://www.vulncheck.com/advisories/xenforo-authentication-bypass-via-oauth2-token-endpoint
- https://xenforo.com/community/threads/security-fixes-released-for-all-xenforo-and-media-gallery-versions-2-2-0-2-3-12.239856/
- https://xenforo.com/community/threads/xenforo-2-3-13-and-add-ons-released-includes-security-fixes.239857/
- https://bombobombone.github.io/posts/cve-2026-73309/
- https://github.com/BomboBombone/CVE-2026-73309
Güvenli Doğrulama Notu
Bu sayfa saldırı gerçekleştiren payload'lar çalıştırmaz. Doğrulama; etkilenen ürün/sürümün envanterden kontrol edilmesi, üretici güvenlik duyurusunun incelenmesi ve güncellemenin uygulanması üzerinden yapılmalıdır.