{"schema_version":"1.7.3","id":"GHSA-f83f-xpx7-ffpw","published":"2025-12-05T18:18:26Z","modified":"2026-02-04T04:23:11.803547Z","aliases":["CVE-2025-66506","GO-2025-4193"],"related":["CGA-63x2-wrq7-39v8"],"summary":"Fulcio allocates excessive memory during token parsing","details":"Function [identity.extractIssuerURL](https://github.com/sigstore/fulcio/blob/main/pkg/identity/issuerpool.go#L44-L45) currently splits (via a call to [strings.Split](https://pkg.go.dev/strings#Split)) its argument (which is untrusted data) on periods.\n\nAs 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. Relevant weakness: [CWE-405: Asymmetric Resource Consumption (Amplification)](https://cwe.mitre.org/data/definitions/405.html)\n\nDetails\nSee [identity.extractIssuerURL](https://github.com/sigstore/fulcio/blob/main/pkg/identity/issuerpool.go#L44-L45)\n\nImpact\nExcessive memory allocation","affected":[{"package":{"name":"github.com/sigstore/fulcio","ecosystem":"Go","purl":"pkg:golang/github.com/sigstore/fulcio"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"1.8.3"}]}],"database_specific":{"last_known_affected_version_range":"<= 1.8.2","source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2025/12/GHSA-f83f-xpx7-ffpw/GHSA-f83f-xpx7-ffpw.json"}}],"references":[{"type":"WEB","url":"https://github.com/sigstore/fulcio/security/advisories/GHSA-f83f-xpx7-ffpw"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-66506"},{"type":"WEB","url":"https://github.com/sigstore/fulcio/commit/765a0e57608b9ef390e1eeeea8595b9054c63a5a"},{"type":"PACKAGE","url":"https://github.com/sigstore/fulcio"}],"database_specific":{"cwe_ids":["CWE-405"],"github_reviewed":true,"github_reviewed_at":"2025-12-05T18:18:26Z","nvd_published_at":"2025-12-04T22:15:49Z","severity":"HIGH"},"severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}