Blind SSRF via unanchored MetaIssuer regex matching
Published Jan 12, 2026 · Updated Jan 12, 2026
SSRF in Sigstore Fulcio before 1.8.5 allows remote attackers to make blind GET requests to internal services through a crafted OIDC issuer URL. The MetaRegex function compiles a wildcard issuer pattern without start or end anchors, so MatchString accepts that pattern anywhere inside an attacker-controlled iss claim. Only deployments using MetaIssuers are affected; responses are not returned, and requests are GET-only, limiting impact to internal network probing without data exfiltration or state changes.
Summary
What happened
SSRF in Sigstore Fulcio before 1.8.5 allows remote attackers to make blind GET requests to internal services through a crafted OIDC issuer URL. The MetaRegex function compiles a wildcard issuer pattern without start or end anchors, so MatchString accepts that pattern anywhere inside an attacker-controlled iss claim. Only deployments using MetaIssuers are affected; responses are not returned, and requests are GET-only, limiting impact to internal network probing without data exfiltration or state changes.
The record
- CVE
- CVE-2026-22772
- Published
- Jan 12, 2026
- Updated
- Jan 12, 2026
- Vendor
- Sigstore
- Product
- Fulcio
- Classifications
- CWE-918, CAPEC-664, T1190, T1046
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jan 12, 2026CVE publishedPublication date reported by the CVE source.
- Jan 12, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 1.8.5
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- GHSA-59jp-pj84-45mr exploit procedureproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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