5.1

CVE-2026-54431: openidc liboauth2

CVSS: 5.1v4.0MediumDeferred
AliasesUBUNTU-CVE-2026-54431DEBIAN-CVE-2026-54431
Published 02-07-2026Last modified 02-07-2026
Open JSON

Vulnerability summary

CVE-2026-54431 is a medium (CVSS 5.1) vulnerability in openidc liboauth2. EPSS estimates a 0.18% chance of exploitation in the next 30 days, higher than 6.9% of scored vulnerabilities.

Overall risk
20/100
0100
Low · default modelHow is this calculated?
CVSS score
5.1/10
010
Medium · v4.0 (CVE.org)
EPSS score
0.18%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 02-07-2026
    PublishedVulnerability first disclosed.
  2. 02-07-2026
    Last modifiedVulnerability information updated.

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

CVSS metrics

4 scores · 4 sources · 1 version

EPSS trend

Probability

0.18%

Chance of exploitation in the next 30 days

Percentile

7%

Versus all other CVEs

30-day change

0.00 pp

From 0.18% on 19-09-2026

19-09-202619-10-2026
EPSS score
0.18%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Debian1 product
  • liboauth2All versions (No fix recorded) | < 2.3.0-1
Openidc1 product
Ubuntu1 product
  • liboauth2All versions (No fix recorded)

3 vendors · 3 products

References

6 links