Unknown · Openid Connect Core · CVE-2025-27370
**Name of the Vulnerable Software and Affected Versions**
OpenID Connect Core versions prior to 1.0 errata set 3
**Description**
The issue 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.
**Recommendations**
For OpenID Connect Core versions prior to 1.0 errata set 3, consider updating to version 1.0 errata set 3 or later to resolve the issue. As a temporary workaround, restrict the use of the private key jwt authentication mechanism to minimize the risk of exploitation.