XenForo < 2.3.13 OAuth2 Authorization Code Reuse
Summary
| CVE | CVE-2026-73311 |
|---|---|
| State | PUBLISHED |
| Assigner | VulnCheck |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-09-08 14:17:25 UTC |
| Updated | 2026-09-11 20:30:43 UTC |
| Description | 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. |
Risk And Classification
Primary CVSS: v4.0 9.1 CRITICAL from [email protected]
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
EPSS: 0.003700000 probability, percentile 0.304360000 (date 2026-09-14)
Problem Types: CWE-294 | CWE-294 Authentication Bypass by Capture-replay
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | [email protected] | Secondary | 9.1 | CRITICAL | 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/C... |
| 4.0 | CNA | CVSS | 9.1 | CRITICAL | 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 |
| 3.1 | [email protected] | Secondary | 7.4 | HIGH | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N |
| 3.1 | CNA | CVSS | 7.4 | HIGH | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N |
CVSS v4.0 Breakdown
Attack Vector
NetworkAttack Complexity
HighAttack Requirements
NonePrivileges Required
NoneUser Interaction
NoneConfidentiality
HighIntegrity
HighAvailability
NoneSub Conf.
NoneSub Integrity
NoneSub Availability
NoneCVSS: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
CVSS v3.1 Breakdown
Attack Vector
NetworkAttack Complexity
HighPrivileges Required
NoneUser Interaction
NoneScope
UnchangedConfidentiality
HighIntegrity
HighAvailability
NoneCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
NVD Known Affected Configurations (CPE 2.3)
Vendor Declared Affected Products
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| xenforo.com/community/threads/security-fixes-released-for-all-xenforo-and... | [email protected] | xenforo.com | Release Notes |
| xenforo.com/community/threads/xenforo-2-3-13-and-add-ons-released-include... | [email protected] | xenforo.com | Release Notes |
| www.vulncheck.com/advisories/xenforo-oauth2-authorization-code-reuse | [email protected] | www.vulncheck.com | Third Party Advisory |
| github.com/BomboBombone/CVE-2026-73311 | [email protected] | github.com | Exploit, Third Party Advisory |
| bombobombone.github.io/posts/cve-2026-73311 | [email protected] | bombobombone.github.io | Exploit, Third Party Advisory |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Marco Paciaroni (BomboBombone) (en)
CNA: VulnCheck (en)
There are currently no legacy QID mappings associated with this CVE.