Server-Side Request Forgery (SSRF) in Fulcio - #VU132351
Published: May 27, 2026
Vulnerability identifier: #VU132351
CSH Severity: High
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:L/SI:N/SA:N/E:U/U:Amber
CVE-ID: N/A
CWE-ID: CWE-918
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Sigstore
Affected software:
Fulcio
Fulcio
Detailed vulnerability description
The vulnerability allows a remote attacker to cause server-side request forgery.
The vulnerability exists due to improper restriction of cross-host redirects in the OIDC discovery client when fetching OIDC discovery metadata. A remote attacker can return a redirect to a different host to cause server-side request forgery.
Remediation
Install security update from vendor's website.