CVE-2026-73310
XenForo < 2.3.13 OAuth2 Authorization Code Token Theft via redirect_uri Bypass
HIGH 8.2EPSS 0.5%
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
- XenForo
- CVSS v4.0 VULNCHECK
- 8.2 HIGH
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:N/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 - CVSS v3.1 NVD
- 5.9 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N - EPSS
- 0.48% chance of exploitation in the next 30 days, 40th percentile
- Published
- 2026-09-08
- Updated
- 2026-10-01
Proof-of-concept exploits (1)
- BomboBombone/CVE-2026-733100★ · 2026-09-08
Security advisories
- https://bombobombone.github.io/posts/cve-2026-73310
- https://www.vulncheck.com/advisories/xenforo-oauth2-authorization-code-token-theft-via-re…
- https://xenforo.com/community/threads/security-fixes-released-for-all-xenforo-and-media-g…
- https://xenforo.com/community/threads/xenforo-2-3-13-and-add-ons-released-includes-securi…