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.
References (2)
Core 2
Core References
Vendor Advisory x_refsource_confirm
https://github.com/sigstore/fulcio/security/advisories/GHSA-59jp-pj84-45mr
Scores
CVSS v3
5.8
EPSS
0.0001
EPSS Percentile
1.9%
Attack Vector
NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N
CISA SSVC
Vulnrichment
Exploitation
poc
Automatable
yes
Technical Impact
partial
Details
CWE
CWE-918
Status
published
Products (2)
linuxfoundation/fulcio
< 1.8.5
sigstore/fulcio
0 - 1.8.5Go
Published
Jan 12, 2026
Tracked Since
Feb 18, 2026