Vulnerability · Published Jul 2, 2026 · Assigned by CERT-PL

CVE-2026-54430Server-Site Request Forgery in liboauth2

Medium 5.1

In plain English

A medium-severity server-side request forgery in liboauth2 from OpenIDC. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 6% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)5.1Medium

Exploit odds (30 days)0.2%top 93.7% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

liboauth2 is vulnerable to Server-Side Request Forgery in oauth2_jose_jwks_aws_alb_resolve() function. The AWS ALB verifier reads both signer and kid from the unverified JWT header. If signer matches the configured ARN, kid is appended to alb_base_url without URL encoding or path sanitization, and the HTTP GET is issued before signature verification. This allows an attacker to force the server to send a GET request to an attacker-chosen internal path. This issue was fixed in version 2.3.0

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Debian:13	liboauth2	no fix listed	DEBIAN-CVE-2026-54430
Debian:14	liboauth2	2.3.0-1	DEBIAN-CVE-2026-54430
Ubuntu:22.04:LTS	liboauth2	no fix listed	UBUNTU-CVE-2026-54430
Ubuntu:24.04:LTS	liboauth2	no fix listed	UBUNTU-CVE-2026-54430
Ubuntu:25.10	liboauth2	no fix listed	UBUNTU-CVE-2026-54430
Ubuntu:26.04:LTS	liboauth2	no fix listed	UBUNTU-CVE-2026-54430
Ubuntu:26.10	liboauth2	no fix listed	UBUNTU-CVE-2026-54430

Affected products (as reported)

Vendor	Product	Versions
OpenIDC	liboauth2	0 – before 2.3.0

Weakness: CWE-918 · Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:N/SA:N

References

https://cert.pl/en/posts/2026/07/CVE-2026-54430 third-party-advisory
https://github.com/OpenIDC/liboauth2 product
https://github.com/OpenIDC/liboauth2/commit/347507ac5b51f48c2933bbe49b2ee07c2af4712b issue-tracking