CVE-2025-66506
Fulcio allocates excessive memory during token parsing
- State
- Published
- Severity
- 7.5 High
- Published
- Dec 4, 2025
- Updated
- Dec 5, 2025
- Reserved
- Dec 3, 2025
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 7.5 High | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | GitHub_M |
Weaknesses
- CWE-405 Asymmetric Resource Consumption (Amplification)
Affected Products
| Product | Versions |
|---|---|
fulciosigstore |
|
References
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