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Vulnerability · Published Aug 13, 2026 · Assigned by GitHub_M

CVE-2026-49478Fulcio has OIDC Discovery Redirect Following Allows SSRF and JWKS Substitution for Meta-Issuer Paths, with Kubernetes Service-Account Token Leakage

High 8.7

In plain English

A high-severity server-side request forgery in fulcio from sigstore. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 21% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)8.7High
Exploit odds (30 days)0.3%top 79.2% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

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 packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:13golang-github-sigstore-fulciono fix listedDEBIAN-CVE-2026-49478
Debian:14golang-github-sigstore-fulcio1.8.7-1DEBIAN-CVE-2026-49478
Gogithub.com/sigstore/fulcio1.8.6GHSA-f5mr-q85p-6hh6
Gogithub.com/sigstore/fulcio1.8.6GO-2026-5853
Ubuntu:26.04:LTSgolang-github-sigstore-fulciono fix listedUBUNTU-CVE-2026-49478

Affected products (as reported)

VendorProductVersions
sigstore fulcio < 1.8.6

Weakness: CWE-918 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N

References