CVE-2026-54431
MEDIUMDescription
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
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
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
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
Low risk: more likely to be exploited than 7% of all known CVEs.
References
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 | 19% | 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 |
Common questions
How do I fix CVE-2026-54431?
Upgrade liboauth2 on debian unstable to 2.3.0-1 or later.
Is CVE-2026-54431 being actively exploited?
Not that we know of. CVE-2026-54431 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.18% is the estimated probability that it will be exploited in the next 30 days. That is higher than 7% of all scored CVEs.
How severe is CVE-2026-54431?
CVE-2026-54431 has a CVSS v4 base score of 5.1, rated medium. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-54431 affect?
Published advisories record a fix for liboauth2 (Debian). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
Embed a live status badge for CVE-2026-54431
Markdown
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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.