CVE-2026-22772

Fulcio vulnerable to Server-Side Request Forgery (SSRF) via MetaIssuer Regex Bypass

Published Jan 12, 2026 CVSS 3.1 · 5.8 Medium EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-59jp-pj84-45mr Fulcio is vulnerable to Server-Side Request Forgery (SSRF) via MetaIssuer Regex Bypass
History
Type Values Removed Values Added
First Time appeared Linuxfoundation
Linuxfoundation fulcio
CPEs cpe:2.3:a:linuxfoundation:fulcio:*:*:*:*:*:*:*:*
Vendors & Products Linuxfoundation
Linuxfoundation fulcio
Type Values Removed Values Added
First Time appeared Sigstore
Sigstore fulcio
Vendors & Products Sigstore
Sigstore fulcio
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
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.
Title Fulcio vulnerable to Server-Side Request Forgery (SSRF) via MetaIssuer Regex Bypass
Weaknesses CWE-918
References
Metrics cvssV3_1

{'score': 5.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Jan 12, 2026, 9:17 PM
Reserved
Jan 9, 2026, 6:27 PM
Status
Analyzed
Published
Jan 12, 2026, 9:15 PM
Modified
Jun 17, 2026, 10:20 AM
Severity
Moderate
Public date
Jan 12, 2026, 8:58 PM