CVE-2026-54431: Openidc LIBOAUTH2

Medium severity, CVSS 5.1. EPSS: 0.2% chance of exploitation in the next 30 days.

In liboauth2 the Demonstrating Proof-of-Possession (DPoP) verifier accepts a proof whose JSON Web Key (jwk) header contains private key material. RFC 9449 section 4.3 step 7 requires the verifier to reject such a proof but oauth2_token_verify() function returns success for a malformed DPoP proof that embeds the private Elliptic Curve (EC) key in the header. This issue was fixed in version 2.3.0

Affected products

• Openidc LIBOAUTH2: before 2.3.0 (fixed in 2.3.0)

Published 2026-07-02. Last modified 2026-07-02.