# CVE-2026-54431

## Summary

- **CVE ID:** CVE-2026-54431
- **Severity:** MEDIUM
- **CVSS Score:** 5.1 (CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N)
- **CWE:** CWE-358
- **Published:** Jul 2, 2026
- **Last Modified:** Jul 2, 2026

## Description

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 (0)

## References

- [CNA](https://cert.pl/en/posts/2026/06/CVE-2026-54430)
- [CNA](https://github.com/OpenIDC/liboauth2)
- [CNA](https://github.com/OpenIDC/liboauth2/commit/c0b57152ed6a0af33aeb04a60bd7f5bff5ab8800)
- [CNA](https://cert.pl/en/posts/2026/07/CVE-2026-54430)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.18%
- **EPSS Percentile:** 7.5

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-11._