{"cve":"CVE-2026-18446","nvd":{"published":"2026-07-31T15:16:27.983","modified":"2026-09-02T14:42:38.677","status":"Analyzed","description":"fast-uri before 4.1.2, 3.1.5, and 2.4.4 requires a literal double forward slash to recognize a URI authority, so a reference that uses a backslash based introducer in place of it (backslash backslash, forward slash backslash, or backslash forward slash) is parsed with no authority and folds into the path. Node's native WHATWG URL parser instead treats a backslash as interchangeable with a forward slash for special schemes, so the two parsers extract different hosts from the same input. Applications that use fast-uri to enforce host based policy such as allowlists, SSRF filtering, or redirect validation before passing the same URL into Node's URL or fetch consumers can be steered to an unintended host. Upgrade to fast-uri 4.1.2, 3.1.5, or 2.4.4.","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:H/A:N","score":7.5},"cwes":["CWE-436"],"references":["https://cna.openjsf.org/security-advisories.html","https://github.com/fastify/fast-uri/security/advisories/GHSA-7p8r-x3mc-p8w7"],"products":["openjsf:fast-uri"],"source":"nvd","synced_at":"2026-10-19T22:47:10.050265369+00:00"},"epss":{"cve":"CVE-2026-18446","score":0.0038,"percentile":0.32009,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-7p8r-x3mc-p8w7","url":"https://osv.dev/vulnerability/GHSA-7p8r-x3mc-p8w7","summary":"fast-uri vulnerable to host confusion via backslash authority introducer","modified":"2026-09-10T03:50:53.468438344Z","packages":[{"ecosystem":"npm","name":"fast-uri","purl":"pkg:npm/fast-uri","ranges":["<2.4.4"],"fixed":["2.4.4"]},{"ecosystem":"npm","name":"fast-uri","purl":"pkg:npm/fast-uri","ranges":[">=3.0.0 <3.1.5"],"fixed":["3.1.5"]},{"ecosystem":"npm","name":"fast-uri","purl":"pkg:npm/fast-uri","ranges":[">=4.0.0 <4.1.2"],"fixed":["4.1.2"]}]}],"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."]}