SSRF in Openidc Liboauth2

CVE-2026-54430

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

Vulnerability class: SSRF (Server-Side Request Forgery)

EPSS: 0.001 (2.3th percentile) — read the EPSS interpretation.