Authentication bypass in OpenID Connect
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- Required
- Attack complexity
- High
- Impact type
- —
- Confidentiality · integrity · availability
- Low · High · None
- Fix status
- No fix listed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA.
Summary
OpenID Connect Core through 1.0 errata set 2 allows audience injection in certain situations. When the private_key_jwt authentication mechanism is used, a malicious Authorization Server could trick a Client into writing attacker-controlled values into the audience, including token endpoints or issuer identifiers of other Authorization Servers. The malicious Authorization Server could then use these private key JWTs to impersonate the Client.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
Remediation
No fixed version listed by the sources yet.
Timeline
- 2026-10-02 Threatist record created from CVE-2025-27370
- 2026-10-03 Alias added: GHSA-pcj4-9fcj-56c8
References
Other 5
- https://openid.net/wp-content/uploads/2025/01/OIDF-Responsible-Disclosure-Notice-on-Security-Vulnerability-for-private_key_jwt.pdf
- https://openid.net/notice-of-a-security-vulnerability/
- https://talks.secworkshop.events/osw2025/talk/R8D9BS/
- https://github.com/OWASP/ASVS/issues/2678
- https://eprint.iacr.org/2025/629
More OpenID vulnerabilities
- TI-2019-08243 Ruby OpenID (aka ruby-openid) through 2.8.0 has a remotely exploitable flaw. CVSS 3.0CRITICAL 9.8
- TI-2007-01592 OpenID allows remote attackers to forcibly log a user into an OpenID enabled site… CVSS 2.0HIGH 7.5
- TI-2007-04984 PHP remote file inclusion vulnerability in includes/openid/Auth/OpenID/BBStore.php in… CVSS 2.0MEDIUM 6.8
- TI-2008-03142 It was found that various OpenID Providers (OPs) had TLS Server Certificates that used… CVSS 3.1MEDIUM 5.9
- TI-2007-01591 Cross-site request forgery (CSRF) vulnerability in OpenID allows remote attackers to… CVSS 2.0MEDIUM 6.8
- TI-2011-03781 message/ax/AxMessage.java in OpenID4Java before 0.9.6 final, as used in JBoss Enterprise… CVSS 2.0MEDIUM 5.8
Sources
- CVE-2025-27370 · CVE Program
- CVE-2025-27370 · NVD
- FIRST EPSS
- GHSA-pcj4-9fcj-56c8 · GitHub Advisory Database · CC BY 4.0
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