{"cve":"CVE-2025-66506","nvd":{"published":"2025-12-04T22:15:49.503","modified":"2026-10-18T15:10:00.097","status":"Analyzed","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_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5},"cwes":["CWE-405"],"references":["https://github.com/sigstore/fulcio/commit/765a0e57608b9ef390e1eeeea8595b9054c63a5a","https://github.com/sigstore/fulcio/security/advisories/GHSA-f83f-xpx7-ffpw"],"products":["linuxfoundation:fulcio"],"source":"nvd","synced_at":"2026-10-19T22:16:40.427100871+00:00"},"epss":{"cve":"CVE-2025-66506","score":0.00211,"percentile":0.11267,"date":"2026-10-25"},"kev":null,"osv":[{"id":"GHSA-f83f-xpx7-ffpw","url":"https://osv.dev/vulnerability/GHSA-f83f-xpx7-ffpw","summary":"Fulcio allocates excessive memory during token parsing","modified":"2026-09-10T03:50:58.558712150Z","packages":[{"ecosystem":"Go","name":"github.com/sigstore/fulcio","purl":"pkg:golang/github.com/sigstore/fulcio","ranges":["<1.8.3"],"fixed":["1.8.3"]}]},{"id":"GO-2025-4193","url":"https://osv.dev/vulnerability/GO-2025-4193","summary":"Fulcio allocates excessive memory during token parsing in github.com/sigstore/fulcio","modified":"2026-02-04T03:55:44.700916Z","packages":[{"ecosystem":"Go","name":"github.com/sigstore/fulcio","purl":"pkg:golang/github.com/sigstore/fulcio","ranges":["<1.8.3"],"fixed":["1.8.3"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}