SSRF in Linuxfoundation Fulcio
CVE-2026-22772
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.
Vulnerability class: SSRF (Server-Side Request Forgery)
EPSS: 0.002 (12.9th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 5.8 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N.
Affected products
- Linuxfoundation Fulcio
- Sigstore Fulcio — versions < 1.8.5
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM, Exploit, Vendor Advisory)
- security-advisories@github.com (Patch, x_refsource_MISC)
Frequently asked questions
- What is CVE-2026-22772?
- CVE-2026-22772 is a medium-severity vulnerability in Linuxfoundation Fulcio, classified under Server-Side Request Forgery (SSRF). CVSS score: 5.8/10. Published 2026-01-12.
- How severe is CVE-2026-22772?
- Medium severity. CVSS v3 base score is 5.8 out of 10.