CVE-2026-49478

Name of the Vulnerable Software and Affected Versions Fulcio versions prior to 1.8.6

Description Fulcio improperly handles cross-host redirects and Kubernetes ServiceAccount tokens during OIDC discovery, specifically when fetching metadata from the /.well-known/openid-configuration endpoint. This leads to three primary issues: first, a malicious issuer can trigger blind Server-Side Request Forgery (SSRF) by redirecting discovery requests to internal systems. Second, an attacker can manipulate the discovery flow to return a malicious jwks uri, allowing them to substitute and poison the verifier cache with malicious JSON Web Key Sets (JWKS) to validate fraudulent signatures. Third, the system may leak Kubernetes ServiceAccount tokens to external hosts if the transport attaches the token globally during redirects or when a wildcard MetaIssuer of type kubernetes matches external endpoints while a local issuer is configured.

Recommendations Update Fulcio to version 1.8.6.