Is CVE-2026-54431 in the CISA KEV catalog?

No. CVE-2026-54431 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-54431?

CVE-2026-54431 has a CVSS v4 base score of 5.1 (MEDIUM).

What is the EPSS score for CVE-2026-54431?

CVE-2026-54431 has an EPSS score of 0.13% (3th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-54431?

Upgrade liboauth2 on debian unstable to 2.3.0-1 or later.

CVE & CISA-KEV Catalog

CVE-2026-54431

MEDIUM

5.1

CVSS v4

NVD

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

CWE-358

How to fix

Remediation Available

liboauth2Debian

Fixed in:2.3.0-1CVE-2026-54431

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v4 Vector

Exploitability

Attack VectorLocal

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

Impact

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Exploit Intelligence

0.13%probability of exploitation in 30 days

3rdpercentile

Low risk: more likely to be exploited than 3% of all known CVEs.

References

Other references3

Related Vulnerabilities

Other CWE-358 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2018-1270	Critical	9.8	77%	-	Fix
CVE-2018-1275	Critical	9.8	58%	-	Fix
CVE-2024-7965	High	8.8	17%	KEV	Fix
CVE-2017-15663	High	7.5	13%	-	-
CVE-2016-10229	Critical	9.8	13%	-	Fix
CVE-2024-2174	High	8.8	13%	-	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-07-02.