What’s Vulnerable › Vulnerabilities

CVE-2026-73310: XenForo < 2.3.13 OAuth2 Authorization Code Token Theft via redirect_uri Bypass

• Severity: medium (CVSS 5.9 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-09-08 · updated 2026-09-11
• Weakness: CWE-863

Description

XenForo before 2.3.13 contains an authorization flaw in the OAuth2 token endpoint that allows attackers controlling any allowlisted redirect URI to bypass redirect URI binding by submitting a different allowlisted URI than the one recorded at authorization time. Attackers can exchange an intercepted authorization code using a mismatched redirect URI to steal OAuth2 tokens from intercepted authorization flows.

Affected products

• XenForo: before 2.3.13 — fixed in 2.3.13

How to fix

Upgrade to a fixed version: XenForo 2.3.13. Check the vendor advisory for mitigations.

References

• https://bombobombone.github.io/posts/cve-2026-73310/
• https://github.com/BomboBombone/CVE-2026-73310
• https://www.vulncheck.com/advisories/xenforo-oauth2-authorization-code-token-theft-via-redirect-uri-bypass
• 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/

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