---
cve: "CVE-2026-54431"
severity: "MEDIUM"
cvss: 5.1
epss: "13%"
vendor: "OpenIDC"
kev: false
exploited: false
published: "2026-07-02 11:16:17"
tags: [cve, security, medium]
source: tsecurity.de CVE-Dossier
exported: "2026-09-13T07:33:54+02:00"
---

# CVE-2026-54431

> 5.1 MEDIUM · 🧪 PoC

## Beschreibung

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

## CVSS-Vektor

```
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
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Lokal | good |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |

## Patch verfügbar (OSV)

- c0b57152ed6a0af33aeb04a60bd7f5bff5ab8800 (Commit)

## Referenzen

- <https://cert.pl/en/posts/2026/07/CVE-2026-54430>
- <https://github.com/OpenIDC/liboauth2>
- <https://github.com/OpenIDC/liboauth2/commit/c0b57152ed6a0af33aeb04a60bd7f5bff5ab8800>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-54431) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_