CVE-2025-27370 (CVSS 6.9)

Description

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.

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CVSS v3.1 Score

6.9

MEDIUM

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:H/A:N

Weakness Type (CWE)

CWE-305 CWE-305

References

Other References

https://eprint.iacr.org/2025/629 https://github.com/OWASP/ASVS/issues/2678 https://openid.net/notice-of-a-security-vulnerability/ https://openid.net/wp-content/uploads/2025/01/OIDF-Responsible-Disclosure-Notice-on-Security-Vulnerability-for-private_key_jwt.pdf https://talks.secworkshop.events/osw2025/talk/R8D9BS/

Frequently Asked Questions

What is CVE-2025-27370? +

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. It has a CVSS v3.1 base score of 6.9 (MEDIUM).

How severe is CVE-2025-27370? +

CVE-2025-27370 has a CVSS v3.1 score of 6.9 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

How do I check if I'm vulnerable to CVE-2025-27370? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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CVE-2025-27370