CVE-2026-54431

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{"bugzilla": {"description": "liboauth2: liboauth2: DPoP verifier accepts malformed proof with private key material", "id": "2496464", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2496464"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.3", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N", "status": "draft"}, "cwe": "CWE-358", "details": ["In liboauth2 the Demonstrating Proof-of-Possession (DPoP) verifier accepts a proof whose JSON Web Key (jwk) header contains private key\u00a0material. RFC 9449 section 4.3 step 7 requires the verifier to reject\u00a0such a proof but\u00a0oauth2_token_verify() function returns success for a malformed DPoP\u00a0proof that embeds the private Elliptic Curve (EC) key in the header.\nThis issue was fixed in version 2.3.0", "A flaw was found in liboauth2. The Demonstrating Proof-of-Possession (DPoP) verifier incorrectly accepts a malformed DPoP proof. This proof contains private key material in its JSON Web Key (JWK) header, which should be rejected according to RFC 9449. This vulnerability could allow an attacker to bypass the intended proof-of-possession mechanism."], "mitigation": {"lang": "en:us", "value": "Ensure DPoP client implementations do not include private key material in\nthe JWK header of DPoP proofs. Review client code to verify only the public\nkey is serialized into the proof's jwk header field. Upgrade liboauth2 to\nversion 2.3.0 or later, which adds server-side rejection of proofs\ncontaining private key material per RFC 9449 section 4.3."}, "name": "CVE-2026-54431", "public_date": "2026-07-02T10:30:57Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-54431\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-54431\nhttps://cert.pl/en/posts/2026/06/CVE-2026-54430\nhttps://github.com/OpenIDC/liboauth2\nhttps://github.com/OpenIDC/liboauth2/commit/c0b57152ed6a0af33aeb04a60bd7f5bff5ab8800"], "statement": "A flaw in liboauth2's DPoP verifier allows it to accept malformed proofs containing private key material, contrary to RFC 9449. This could enable an attacker to bypass the proof-of-possession mechanism, potentially compromising the integrity of token validation in applications utilizing the library. The impact is limited to applications that implement DPoP using liboauth2 and do not perform additional validation.", "threat_severity": "Moderate"}

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