CVE-2026-73311
HIGHDescription
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.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Exploit Intelligence
Low risk: more likely to be exploited than 31% of all known CVEs.
References
Related Vulnerabilities
Other CWE-294 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2023-23397 | Critical | 9.8 | 97% | KEV | Fix |
| CVE-2017-3191 | Critical | 9.8 | 63% | - | - |
| CVE-2023-49231 | Critical | 9.8 | 43% | - | - |
| CVE-2002-0054 | High | 7.5 | 22% | - | - |
| CVE-2022-29593 | Medium | 5.9 | 14% | - | - |
| CVE-2022-22806 | Critical | 9.8 | 12% | - | - |
Common questions
How do I fix CVE-2026-73311?
Upgrade xenforo to 2.3.13 or later.
Is CVE-2026-73311 being actively exploited?
Not that we know of. CVE-2026-73311 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.37% is the estimated probability that it will be exploited in the next 30 days. That is higher than 31% of all scored CVEs.
How severe is CVE-2026-73311?
CVE-2026-73311 has a CVSS v3 base score of 7.4, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-73311 affect?
Published advisories record a fix for xenforo (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-09-11.