CVE-2026-49478: Sigstore Fulcio

High severity, CVSS 8.7. EPSS: 0.3% chance of exploitation in the next 30 days.

Fulcio is a certificate authority for issuing code signing certificates for an OpenID Connect (OIDC) identity. Versions through 1.8.5 improperly follow cross-host redirects and attach Kubernetes ServiceAccount tokens during OIDC discovery, allowing a malicious or compromised issuer to perform blind SSRF, substitute and cache malicious JWKS keys, or disclose ServiceAccount tokens to external hosts. Version 1.8.6 blocks cross-host redirects, restricts token injection, and restricts local token loading. No known workarounds are available.

Affected products

• Sigstore Fulcio: before 1.8.6 (fixed in 1.8.6)

Published 2026-08-13. Last modified 2026-09-09.