Vulnerability · Published Jan 12, 2026 · Assigned by GitHub_M
CVE-2026-22772Fulcio vulnerable to Server-Side Request Forgery (SSRF) via MetaIssuer Regex Bypass
Medium 5.8
In plain English
A medium-severity server-side request forgery in fulcio from sigstore. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 14% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Fulcio is a certificate authority for issuing code signing certificates for an OpenID Connect (OIDC) identity. Prior to 1.8.5, Fulcio's metaRegex() function uses unanchored regex, allowing attackers to bypass MetaIssuer URL validation and trigger SSRF to arbitrary internal services. Since the SSRF only can trigger GET requests, the request cannot mutate state. The response from the GET request is not returned to the caller so data exfiltration is not possible. A malicious actor could attempt to probe an internal network through Blind SSRF. This vulnerability is fixed in 1.8.5.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:13 | golang-github-sigstore-fulcio | no fix listed | DEBIAN-CVE-2026-22772 |
| Debian:14 | golang-github-sigstore-fulcio | 1.8.5-1 | DEBIAN-CVE-2026-22772 |
| Go | github.com/sigstore/fulcio | 1.8.5 | GO-2026-4311 |
| Go | github.com/sigstore/fulcio | 1.8.5 | GHSA-59jp-pj84-45mr |
| Ubuntu:25.10 | golang-github-sigstore-fulcio | no fix listed | UBUNTU-CVE-2026-22772 |
| Ubuntu:26.04:LTS | golang-github-sigstore-fulcio | no fix listed | UBUNTU-CVE-2026-22772 |
| Ubuntu:26.10 | golang-github-sigstore-fulcio | no fix listed | UBUNTU-CVE-2026-22772 |
Affected products (as reported)
Weakness: CWE-918 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N