CRITICAL 9.1 NVD
CVE-2026-73311
XenForo before 2.3.13 contains an OAuth2 authorization code reuse vulnerability that allows attackers to obtain unauthorized token pairs by submitting a previou
XenForo before 2.3.13 contains an OAuth2 authorization code reuse vulnerability that allows attackers to obtain unauthorized token pairs by submitting a previously used authorization code. Attackers can exploit the failure to invalidate or mark authorization codes as consumed after initial token issuance to receive an independent token pair for the same user and scopes, bypassing the single-use guarantee of the OAuth2 authorization code flow.
Affected Products
- xenforo/xenforo
References
- https://bombobombone.github.io/posts/cve-2026-73311/
- https://github.com/BomboBombone/CVE-2026-73311
- https://www.vulncheck.com/advisories/xenforo-oauth2-authorization-code-reuse
- https://xenforo.com/community/threads/security-fixes-released-for-all-xenforo-and-media-ga
- https://xenforo.com/community/threads/xenforo-2-3-13-and-add-ons-released-includes-securit
This critical severity vulnerability with a CVSS score of 9.1 was published on 2026-09-08 via NVD. Affected: xenforo/xenforo.
Risk Timeline
CVE Disclosed2026-09-08 · 2 days ago
Remediation Resources
Official Advisory
bombobombone.github.io/posts/cve-2026-73311/Official Advisory
www.vulncheck.com/advisories/xenforo-oauth2-authorization-code-reuseRelated Vulnerabilities
| CVE | Title | Severity | CVSS |
|---|---|---|---|
| CVE-2026-73309 | XenForo before 2.3.13 contains an authentication bypass vulnerability in the OAu | CRITICAL | 9.1 |
| CVE-2026-73312 | XenForo before 2.3.13 contains a refresh token replay vulnerability that allows | CRITICAL | 9.1 |
| CVE-2026-73314 | XenForo before 2.3.13 contains a signature verification logic error in the PayPa | HIGH | 8.7 |
| CVE-2026-73316 | XenForo before 2.3.13 contains a payment replay vulnerability in the PayPal REST | HIGH | 8.7 |
| CVE-2026-74239 | XenForo before 2.3.13 contains a path traversal vulnerability in the style archi | HIGH | 8.6 |
| CVE-2026-73310 | XenForo before 2.3.13 contains an authorization flaw in the OAuth2 token endpoin | HIGH | 8.2 |
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