Fulcio vulnerable to Server-Side Request Forgery (SSRF) via MetaIssuer Regex Bypass (sigstore fulcio)
At a glance
- Source
- NVD
- EPSS
- EPSS 0.23 % · percentile 14 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- GitHub_M
- NVD status
- Analyzed
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.
Weaknesses (CWE)
- CWE-918 — Server-Side Request Forgery
References
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 3.1 | MEDIUM 5.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N | GitHub_M |
| CVSS 3.1 | MEDIUM 5.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N | NVD · security-advisories@github.com (Secondary) |
| CVSS 3.1 | MEDIUM 5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N | NVD · nvd@nist.gov (Primary) |
Advisories
- GHSA-59jp-pj84-45mr — Fulcio is vulnerable to Server-Side Request Forgery (SSRF) via MetaIssuer Regex Bypass
- GO-2026-4311 — Fulcio is vulnerable to Server-Side Request Forgery (SSRF) via MetaIssuer Regex Bypass in github.com/sigstore/fulcio
European references
- ENISA EUVD · EUVD-2026-2001
- GCVE · GCVE-0-2026-22772
Affected configurations (NVD CPE)
cpe:2.3:a:linuxfoundation:fulcio:*:*:*:*:*:*:*:*< 1.8.5
Affected products
| Product | Versions |
|---|---|
| sigstore · fulcio | affected < 1.8.5 |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |