OAuth2 token theft via redirect URI mismatch
Published Sep 8, 2026 · Updated Sep 9, 2026
Incorrect authorization in XenForo before 2.3.13 allows remote attackers to steal OAuth2 tokens through the token endpoint. The endpoint accepts any allowlisted redirect URI during code exchange instead of requiring the URI recorded when the authorization code was issued. Exploitation requires control of an allowlisted URI and an intercepted authorization code, granting access authorized by the stolen token.
Summary
What happened
Incorrect authorization in XenForo before 2.3.13 allows remote attackers to steal OAuth2 tokens through the token endpoint. The endpoint accepts any allowlisted redirect URI during code exchange instead of requiring the URI recorded when the authorization code was issued. Exploitation requires control of an allowlisted URI and an intercepted authorization code, granting access authorized by the stolen token.
The record
- CVE
- CVE-2026-73310
- Published
- Sep 8, 2026
- Updated
- Sep 9, 2026
- Vendor
- XenForo Ltd.
- Product
- XenForo
- Classifications
- CWE-863, T1528
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 8, 2026CVE publishedPublication date reported by the CVE source.
- Sep 9, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <2.3.13
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
- CVE-2026-73310 proof of conceptproof of concept · unverified
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Technologies
Your stack
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Your stack
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