CVE-2026-54431
Improper Data Validation in liboauth2
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
INFO
Published Date :
July 2, 2026, 11:16 a.m.
Last Modified :
July 2, 2026, 5:43 p.m.
Remotely Exploit :
No
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-54431
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 4.0 | MEDIUM | 4bb8329e-dd38-46c1-aafb-9bf32bcb93c6 | ||||
| CVSS 4.0 | MEDIUM | [email protected] |
Solution
- Update liboauth2 to version 2.3.0.
- Ensure DPoP verifier rejects private JWK headers.
Public PoC/Exploit Available at Github
CVE-2026-54431 has a 1 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-54431.
| URL | Resource |
|---|---|
| https://cert.pl/en/posts/2026/07/CVE-2026-54430 | |
| https://github.com/OpenIDC/liboauth2 | |
| https://github.com/OpenIDC/liboauth2/commit/c0b57152ed6a0af33aeb04a60bd7f5bff5ab8800 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-54431 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-54431
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
CVEs, conference materials, research.
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-54431 vulnerability anywhere in the article.
-
cert.pl
Vulnerabilities in OpenIDC liboauth2 software
Vulnerabilities in OpenIDC liboauth2 software CVE ID CVE-2026-54430 Publication date 02 July 2026 Vendor OpenIDC Product liboauth2 Vulnerable versions All before 2.3.0 Vulnerability type (CWE) Server- ... Read more
The following table lists the changes that have been made to the
CVE-2026-54431 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jul. 02, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-54431', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-07-02T12:16:34.432412Z'} -
CVE Modified by [email protected]
Jul. 02, 2026
Action Type Old Value New Value Added Reference https://cert.pl/en/posts/2026/07/CVE-2026-54430 Removed Reference https://cert.pl/en/posts/2026/06/CVE-2026-54430 -
New CVE Received by [email protected]
Jul. 02, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://github.com/OpenIDC/liboauth2', 'vendor': 'OpenIDC', 'product': 'liboauth2', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '2.3.0', 'versionType': 'semver'}], 'programFiles': ['src/dpop.c'], 'defaultStatus': 'unaffected', 'programRoutines': [{'name': '_oauth2_dpop_parse_and_validate()'}]}] Added 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 Added CVSS V4.0 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 Added CWE CWE-358 Added Reference https://cert.pl/en/posts/2026/06/CVE-2026-54430 Added Reference https://github.com/OpenIDC/liboauth2 Added Reference https://github.com/OpenIDC/liboauth2/commit/c0b57152ed6a0af33aeb04a60bd7f5bff5ab8800