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

Severity: medium (CVSS 5.1 v4.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-07-02 · updated 2026-10-25
Weakness: CWE-918

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 products

OpenIDC liboauth2: before 2.3.0 — fixed in 2.3.0

How to fix

Upgrade to a fixed version: OpenIDC liboauth2 2.3.0. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2026-54430 or the next vulnerability affects your stack