Vulnerability Description
Fulcio is a free-to-use certificate authority for issuing code signing certificates for an OpenID Connect (OIDC) identity. Prior to 1.8.3, function identity.extractIssuerURL splits (via a call to strings.Split) its argument (which is untrusted data) on periods. As a result, in the face of a malicious request with an (invalid) OIDC identity token in the payload containing many period characters, a call to extractIssuerURL incurs allocations to the tune of O(n) bytes (where n stands for the length of the function's argument), with a constant factor of about 16. This vulnerability is fixed in 1.8.3.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Linuxfoundation | Fulcio | < 1.8.3 |
Related Weaknesses (CWE)
References
- https://github.com/sigstore/fulcio/commit/765a0e57608b9ef390e1eeeea8595b9054c63aPatch
- https://github.com/sigstore/fulcio/security/advisories/GHSA-f83f-xpx7-ffpwVendor Advisory
FAQ
What is CVE-2025-66506?
CVE-2025-66506 is a vulnerability with a CVSS score of 7.5 (HIGH). Fulcio is a free-to-use certificate authority for issuing code signing certificates for an OpenID Connect (OIDC) identity. Prior to 1.8.3, function identity.extractIssuerURL splits (via a call to stri...
How severe is CVE-2025-66506?
CVE-2025-66506 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2025-66506?
Check the references section above for vendor advisories and patch information. Affected products include: Linuxfoundation Fulcio.