{"id":"CVE-2026-16221","aliases":["CLSA-2026-1784682957","CLSA-2026-1784769538","CLSA-2026-1784769612","CLSA-2026-1790893546","CLSA-2026-1791370091","CLSA-2026-1791814871","CLSA-2026-1792143884","DEBIAN-CVE-2026-16221","EUVD-2026-45551","GHSA-v2hh-gcrm-f6hx","RHSA-2026:54517","RHSA-2026:54518","ROOT-APP-NPM-CVE-2026-16221","UBUNTU-CVE-2026-16221"],"status":"published","title":"fast-uri vulnerable to host confusion via literal backslash authority delimiter","description":"Impact: fast-uri versions from 2.3.1 through 4.1.0 (including the 3.x line up to 3.1.3 and the 2.x line up to 2.4.2) do not treat a literal backslash character (U+005C) as an authority delimiter. Node's native WHATWG URL parser, used by fetch, undici, and Node's http and https clients, normalizes the backslash to a forward slash for special schemes such as http, https, ws, wss, ftp, and file. As a result, the two parsers extract different hosts from the same input string. Applications that use fast-uri to enforce host-based policy such as allowlists, denylists, loopback or SSRF filtering, redirect validation, or outbound proxy routing before passing the same URL into Node's URL or fetch consumers can be steered to an unintended destination, including cloud metadata endpoints, loopback, or internal hosts. \n\nPatches: upgrade to fast-uri 4.1.1, 3.1.4, or 2.4.3.\n\nWorkarounds: none.","severity":{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.00436,"percentile":0.38326,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-436"],"published":"2026-07-19T14:08:32Z","modified":"2026-11-05T11:15:09Z","fixes":[{"ecosystem":"npm","package":"fast-uri","fixed_in":["2.4.3","3.1.4","4.1.1"],"sources":["ghsa","osv"]},{"ecosystem":"TuxCare:npm","package":"fast-uri","fixed_in":["3.0.1-tuxcare.2","3.1.2-tuxcare.3","3.1.3-tuxcare.5"],"sources":["osv"]},{"ecosystem":"Debian:14","package":"node-ajv","fixed_in":["8.20.0~ds+~cs7.1.2-1"],"sources":["osv"]},{"ecosystem":"Root:npm","package":"fast-uri","fixed_in":["3.0.1-aikido.4","3.0.1-aikido.5","3.0.2-aikido.6","3.1.0-aikido.6","3.0.6-aikido.5","3.1.2-aikido.3","3.0.1-aikido.6","3.0.6-aikido.3","3.1.2-aikido.1","3.0.1-aikido.7","3.0.6-aikido.4","3.1.0-aikido.5","3.1.2-aikido.2","3.0.2-aikido.5","3.1.3-aikido.2","3.0.3-aikido.5","3.0.6-aikido.6","3.0.3-aikido.6","3.0.3-aikido.7","3.0.1-aikido.8","3.0.3-aikido.8","3.1.2-aikido.4","3.0.3-aikido.9","3.1.3-aikido.3"],"sources":["osv"]},{"ecosystem":"Root:npm","package":"@rootio/fast-uri","fixed_in":["3.0.1-root.io.4","3.0.1-root.io.5","3.0.2-root.io.6","3.1.0-root.io.6","3.0.6-root.io.5","3.1.2-root.io.3","3.0.1-root.io.6","3.0.6-root.io.3","3.1.2-root.io.1","3.0.1-root.io.7","3.0.6-root.io.4","3.1.0-root.io.5","3.1.2-root.io.2","3.0.2-root.io.5","3.1.3-root.io.2","3.0.3-root.io.5","3.0.6-root.io.6","3.0.3-root.io.6","3.0.3-root.io.7","3.0.1-root.io.8","3.0.3-root.io.8","3.1.2-root.io.4","3.0.3-root.io.9","3.1.3-root.io.3"],"sources":["osv"]}],"affected":[{"source":"ghsa","ecosystem":"npm","package":"fast-uri","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"2.3.1"},{"last_affected":"2.4.2"},{"fixed":"2.4.3"}]}]},{"source":"ghsa","ecosystem":"npm","package":"fast-uri","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.0.0"},{"last_affected":"3.1.3"},{"fixed":"3.1.4"}]}]},{"source":"ghsa","ecosystem":"npm","package":"fast-uri","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.0.0"},{"last_affected":"4.1.0"},{"fixed":"4.1.1"}]}]},{"source":"osv","ecosystem":"TuxCare:npm","package":"fast-uri","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.0.3-tuxcare.0"},{"fixed":"3.0.3-tuxcare.2"}]}],"versions":["3.0.3","3.0.3-tuxcare.1"],"bundled":2},{"source":"osv","ecosystem":"TuxCare:npm","package":"fast-uri","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.0.1-tuxcare.0"},{"fixed":"3.0.1-tuxcare.2"}]}],"versions":["3.0.1","3.0.1-tuxcare.1"]},{"source":"osv","ecosystem":"TuxCare:npm","package":"fast-uri","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"2.4.2-tuxcare.0"},{"fixed":"2.4.2-tuxcare.1"}]}],"versions":["2.4.2"],"bundled":6},{"source":"osv","ecosystem":"TuxCare:npm","package":"fast-uri","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.1.2-tuxcare.0"},{"fixed":"3.1.2-tuxcare.3"}]}],"versions":["3.1.2","3.1.2-tuxcare.1","3.1.2-tuxcare.2"]},{"source":"osv","ecosystem":"TuxCare:npm","package":"fast-uri","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.1.3-tuxcare.0"},{"fixed":"3.1.3-tuxcare.5"}]}],"versions":["3.1.3","3.1.3-tuxcare.1","3.1.3-tuxcare.2","3.1.3-tuxcare.3","3.1.3-tuxcare.4"]},{"source":"osv","ecosystem":"TuxCare:npm","package":"fast-uri","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.1.0-tuxcare.0"},{"fixed":"3.1.0-tuxcare.3"}]}],"versions":["3.1.0","3.1.0-tuxcare.1","3.1.0-tuxcare.2"],"bundled":5},{"source":"osv","ecosystem":"TuxCare:npm","package":"fast-uri","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.0.6-tuxcare.0"},{"fixed":"3.0.6-tuxcare.2"}]}],"versions":["3.0.6","3.0.6-tuxcare.1"],"bundled":7},{"source":"osv","ecosystem":"Debian:13","package":"node-ajv","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["8.12.0~ds+~2.1.1-5","8.17.1~ds+~3.0.1+~3.1.0-1","8.17.1~ds+~3.0.1+~3.1.0-2","8.17.1~ds+~3.0.1+~3.1.0-3","8.17.1~ds+~3.0.1+~3.1.0-4","8.18.0~ds+~cs6.1.1-1","8.18.0~ds+~cs6.1.1-2","8.20.0~ds+~cs6.1.3-1","8.20.0~ds+~cs7.1.2-1","8.20.0~ds+~cs7.1.3-1","8.20.0~ds+~cs7.1.3-2","8.20.0~ds+~cs7.1.3-3","8.20.0~ds+~cs7.1.4-1","8.20.0~ds+~cs7.1.5-1","8.20.0~ds+~cs7.1.6-1"]},{"source":"osv","ecosystem":"Debian:14","package":"node-ajv","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"8.20.0~ds+~cs7.1.2-1"}]}],"versions":["8.12.0~ds+~2.1.1-5","8.17.1~ds+~3.0.1+~3.1.0-1","8.17.1~ds+~3.0.1+~3.1.0-2","8.17.1~ds+~3.0.1+~3.1.0-3","8.17.1~ds+~3.0.1+~3.1.0-4","8.18.0~ds+~cs6.1.1-1","8.18.0~ds+~cs6.1.1-2","8.20.0~ds+~cs6.1.3-1"]},{"source":"osv","ecosystem":"npm","package":"fast-uri","ranges":[{"type":"SEMVER","events":[{"introduced":"2.3.1"},{"fixed":"2.4.3"}]}]},{"source":"osv","ecosystem":"npm","package":"fast-uri","ranges":[{"type":"SEMVER","events":[{"introduced":"3.0.0"},{"fixed":"3.1.4"}]}]},{"source":"osv","ecosystem":"npm","package":"fast-uri","ranges":[{"type":"SEMVER","events":[{"introduced":"4.0.0"},{"fixed":"4.1.1"}]}]},{"source":"osv","ecosystem":"Red Hat:hummingbird:1","package":"grafana13.1","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0:13.1.3-0.1.1.hum1"}]}],"bundled":9},{"source":"osv","ecosystem":"Red Hat:hummingbird:1","package":"grafana12.4","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0:12.4.8-0.1.1.hum1"}]}],"bundled":5},{"source":"osv","ecosystem":"Root:npm","package":"fast-uri","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.0.1-aikido.4"},{"fixed":"3.0.1-aikido.5"},{"fixed":"3.0.2-aikido.6"},{"fixed":"3.1.0-aikido.6"},{"fixed":"3.0.6-aikido.5"},{"fixed":"3.1.2-aikido.3"},{"fixed":"3.0.1-aikido.6"},{"fixed":"3.0.6-aikido.3"},{"fixed":"3.1.2-aikido.1"},{"fixed":"3.0.1-aikido.7"},{"fixed":"3.0.6-aikido.4"},{"fixed":"3.1.0-aikido.5"},{"fixed":"3.1.2-aikido.2"},{"fixed":"3.0.2-aikido.5"},{"fixed":"3.1.3-aikido.2"},{"fixed":"3.0.3-aikido.5"},{"fixed":"3.0.6-aikido.6"},{"fixed":"3.0.3-aikido.6"},{"fixed":"3.0.3-aikido.7"},{"fixed":"3.0.1-aikido.8"},{"fixed":"3.0.3-aikido.8"},{"fixed":"3.1.2-aikido.4"},{"fixed":"3.0.3-aikido.9"},{"fixed":"3.1.3-aikido.3"}]}]},{"source":"osv","ecosystem":"Root:npm","package":"@rootio/fast-uri","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.0.1-root.io.4"},{"fixed":"3.0.1-root.io.5"},{"fixed":"3.0.2-root.io.6"},{"fixed":"3.1.0-root.io.6"},{"fixed":"3.0.6-root.io.5"},{"fixed":"3.1.2-root.io.3"},{"fixed":"3.0.1-root.io.6"},{"fixed":"3.0.6-root.io.3"},{"fixed":"3.1.2-root.io.1"},{"fixed":"3.0.1-root.io.7"},{"fixed":"3.0.6-root.io.4"},{"fixed":"3.1.0-root.io.5"},{"fixed":"3.1.2-root.io.2"},{"fixed":"3.0.2-root.io.5"},{"fixed":"3.1.3-root.io.2"},{"fixed":"3.0.3-root.io.5"},{"fixed":"3.0.6-root.io.6"},{"fixed":"3.0.3-root.io.6"},{"fixed":"3.0.3-root.io.7"},{"fixed":"3.0.1-root.io.8"},{"fixed":"3.0.3-root.io.8"},{"fixed":"3.1.2-root.io.4"},{"fixed":"3.0.3-root.io.9"},{"fixed":"3.1.3-root.io.3"}]}]},{"source":"osv","ecosystem":"Ubuntu:18.04:LTS","package":"node-ajv","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["5.0.0-1"]},{"source":"osv","ecosystem":"Ubuntu:20.04:LTS","package":"node-ajv","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["6.10.2-1"]},{"source":"osv","ecosystem":"Ubuntu:22.04:LTS","package":"node-ajv","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["6.12.6-2","6.12.6-3"]},{"source":"osv","ecosystem":"Ubuntu:24.04:LTS","package":"node-ajv","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["6.12.6-3","8.12.0~ds+~2.1.1-4"]},{"source":"osv","ecosystem":"Ubuntu:26.10","package":"node-ajv","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["8.17.1~ds+~3.0.1+~3.1.0-4build1","8.20.0~ds+~cs6.1.3-1","8.20.0~ds+~cs7.1.2-1","8.20.0~ds+~cs7.1.3-1","8.20.0~ds+~cs7.1.3-3"]},{"source":"osv","ecosystem":"Ubuntu:26.04:LTS","package":"node-ajv","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["8.12.0~ds+~2.1.1-5","8.17.1~ds+~3.0.1+~3.1.0-2","8.17.1~ds+~3.0.1+~3.1.0-4build1"]}],"products":[{"vendor":"fast-uri","product":"fast-uri"},{"vendor":"openjsf","product":"fast-uri"}],"references":[{"url":"https://github.com/fastify/fast-uri/security/advisories/GHSA-v2hh-gcrm-f6hx","tags":["Vendor Advisory","advisory","web","article","report"]},{"url":"https://cna.openjsf.org/security-advisories.html","tags":["Vendor Advisory","advisory","web","article"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-16221","tags":["advisory"]},{"url":"https://github.com/fastify/fast-uri/commit/0542a216860fd70c062a4730e620576f62ded057","tags":["web"]},{"url":"https://github.com/fastify/fast-uri/commit/2d50fbabc80e4d0884fe0f6a98fe118ce6faa353","tags":["web"]},{"url":"https://github.com/fastify/fast-uri/commit/9438266d6a7ded688c8bc7c4ba506da17f44a17b","tags":["web"]},{"url":"https://github.com/fastify/fast-uri/releases/tag/v2.4.3","tags":["web"]},{"url":"https://github.com/fastify/fast-uri/releases/tag/v3.1.4","tags":["web"]},{"url":"https://github.com/fastify/fast-uri/releases/tag/v4.1.1","tags":["web"]},{"url":"https://github.com/advisories/GHSA-v2hh-gcrm-f6hx"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/16xxx/CVE-2026-16221.json","tags":["advisory"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-16221","tags":["advisory"]},{"url":"https://github.com/fastify/fast-uri","tags":["package"]},{"url":"https://access.redhat.com/errata/RHSA-2026:54517","tags":["advisory"]},{"url":"https://access.redhat.com/security/cve/CVE-2026-73088","tags":["report"]},{"url":"https://access.redhat.com/security/cve/CVE-2026-73089","tags":["report"]},{"url":"https://access.redhat.com/security/updates/classification/","tags":["article"]},{"url":"https://images.redhat.com/","tags":["article"]},{"url":"https://access.redhat.com/security/cve/CVE-2026-45819","tags":["report"]},{"url":"https://access.redhat.com/security/cve/CVE-2026-16221","tags":["report"]},{"url":"https://access.redhat.com/security/cve/CVE-2026-65904","tags":["report"]},{"url":"https://access.redhat.com/security/cve/CVE-2026-65912","tags":["report"]},{"url":"https://access.redhat.com/security/cve/CVE-2026-65911","tags":["report"]},{"url":"https://access.redhat.com/security/cve/CVE-2026-65914","tags":["report"]},{"url":"https://access.redhat.com/security/cve/CVE-2026-65913","tags":["report"]},{"url":"https://security.access.redhat.com/data/csaf/v2/advisories/2026/rhsa-2026_54517.json","tags":["advisory"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2502307","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-16221","tags":["advisory","report"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2515240","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-45819","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-45819","tags":["advisory"]},{"url":"https://github.com/web-platform-dx/baseline-browser-mapping/blob/b7881aa61c8a057e24468ab5ee18c5ecedbbf691/src/index.ts#L142","tags":["article"]},{"url":"https://github.com/web-platform-dx/baseline-browser-mapping/pull/137/changes#diff-7ae45ad102eab3b6d7e7896acd08c427a9b25b346470d7bc6507b6481575d519","tags":["article"]},{"url":"https://www.npmjs.com/package/baseline-browser-mapping","tags":["article"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2506426","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-65904","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-65904","tags":["advisory"]},{"url":"https://github.com/cure53/DOMPurify/security/advisories/GHSA-4w3q-35jp-p934","tags":["article"]},{"url":"https://www.vulncheck.com/advisories/dompurify-before-cross-site-scripting-via-in-place-mode","tags":["article"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2506434","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-65911","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-65911","tags":["advisory"]},{"url":"https://github.com/cure53/DOMPurify/security/advisories/GHSA-9p3w-6h5p-cv75","tags":["article"]},{"url":"https://www.vulncheck.com/advisories/dompurify-before-xss-via-add-attr-add-tags-state-leakage","tags":["article"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2506427","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-65912","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-65912","tags":["advisory"]},{"url":"https://github.com/cure53/DOMPurify/security/advisories/GHSA-cjmm-f4jc-qw8r","tags":["article"]},{"url":"https://www.vulncheck.com/advisories/dompurify-before-uri-validation-bypass-via-add-attr","tags":["article"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2506429","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-65913","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-65913","tags":["advisory"]},{"url":"https://github.com/cure53/DOMPurify/security/advisories/GHSA-cj63-jhhr-wcxv","tags":["article"]},{"url":"https://www.vulncheck.com/advisories/dompurify-before-prototype-pollution-via-use-profiles","tags":["article"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2506430","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-65914","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-65914","tags":["advisory"]},{"url":"https://github.com/cure53/DOMPurify/security/advisories/GHSA-h8r8-wccr-v5f2","tags":["article"]},{"url":"https://www.vulncheck.com/advisories/dompurify-before-mutation-xss-via-re-contextualization","tags":["article"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2514177","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-73088","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-73088","tags":["advisory"]},{"url":"https://github.com/browserslist/browserslist/commit/f9914ad9effc865ccc27d816255625890b31ca51","tags":["article"]},{"url":"https://github.com/browserslist/browserslist/releases/tag/4.28.7","tags":["article"]},{"url":"https://github.com/browserslist/browserslist/security/advisories/GHSA-73wf-gq98-2v4g","tags":["article"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2514195","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-73089","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-73089","tags":["advisory"]},{"url":"https://github.com/browserslist/browserslist/commit/f2931a3ff2a3a31abf84ef01a7400b270aad6405","tags":["article"]},{"url":"https://github.com/browserslist/browserslist/security/advisories/GHSA-c83g-rgw3-j3cx","tags":["article"]},{"url":"https://access.redhat.com/errata/RHSA-2026:54518","tags":["advisory"]},{"url":"https://access.redhat.com/security/cve/CVE-2026-73086","tags":["report"]},{"url":"https://security.access.redhat.com/data/csaf/v2/advisories/2026/rhsa-2026_54518.json","tags":["advisory"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2514175","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-73086","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-73086","tags":["advisory"]},{"url":"https://github.com/ai/nanoid/commit/7087969281cab8ba8ae3babf1894e819068b3bb4","tags":["article"]},{"url":"https://github.com/ai/nanoid/commit/821dfed7b5db7f88e92f56c60eef32c8135077c3","tags":["article"]},{"url":"https://github.com/ai/nanoid/commit/b0036ed60dc9facd7f1191a50dfb3076500202ac","tags":["article"]},{"url":"https://github.com/ai/nanoid/releases/tag/3.3.12","tags":["article"]},{"url":"https://github.com/ai/nanoid/releases/tag/5.1.11","tags":["article"]},{"url":"https://github.com/ai/nanoid/security/advisories/GHSA-xwg4-73v4-xw9w","tags":["article"]},{"url":"https://ubuntu.com/security/CVE-2026-16221","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2026-16221","title":"fast-uri vulnerable to host confusion via literal backslash authority delimiter","description":"Impact: fast-uri versions from 2.3.1 through 4.1.0 (including the 3.x line up to 3.1.3 and the 2.x line up to 2.4.2) do not treat a literal backslash character (U+005C) as an authority delimiter. Node's native WHATWG URL parser, used by fetch, undici, and Node's http and https clients, normalizes the backslash to a forward slash for special schemes such as http, https, ws, wss, ftp, and file. As a result, the two parsers extract different hosts from the same input string. Applications that use fast-uri to enforce host-based policy such as allowlists, denylists, loopback or SSRF filtering, redirect validation, or outbound proxy routing before passing the same URL into Node's URL or fetch consumers can be steered to an unintended destination, including cloud metadata endpoints, loopback, or internal hosts. \n\nPatches: upgrade to fast-uri 4.1.1, 3.1.4, or 2.4.3.\n\nWorkarounds: none.","status":"published","published":"2026-07-19T14:08:32.993Z","modified":"2026-07-20T13:53:42.583Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","level":"high","assessor":"cna"}],"cwes":["CWE-436"],"updated_at":"2026-11-02T14:20:11.24076Z"}],"euvd":[{"id":"EUVD-2026-45551","description":"Impact: fast-uri versions from 2.3.1 through 4.1.0 (including the 3.x line up to 3.1.3 and the 2.x line up to 2.4.2) do not treat a literal backslash character (U+005C) as an authority delimiter. Node's native WHATWG URL parser, used by fetch, undici, and Node's http and https clients, normalizes the backslash to a forward slash for special schemes such as http, https, ws, wss, ftp, and file. As a result, the two parsers extract different hosts from the same input string. Applications that use fast-uri to enforce host-based policy such as allowlists, denylists, loopback or SSRF filtering, redirect validation, or outbound proxy routing before passing the same URL into Node's URL or fetch consumers can be steered to an unintended destination, including cloud metadata endpoints, loopback, or internal hosts. \n\nPatches: upgrade to fast-uri 4.1.1, 3.1.4, or 2.4.3.\n\nWorkarounds: none.","status":"published","published":"2026-07-19T14:08:32Z","modified":"2026-07-20T13:53:42Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","level":"high"}],"updated_at":"2026-11-02T18:19:49.035342Z"}],"ghsa":[{"id":"GHSA-v2hh-gcrm-f6hx","title":"fast-uri vulnerable to host confusion via literal backslash authority delimiter","description":"### Impact\n\n`fast-uri` v4.1.0 and earlier do not treat a literal backslash (U+005C) as an authority delimiter. Node's native WHATWG `URL` (used by `fetch()`, `undici`, and Node's `http`/`https` clients) normalizes `\\` to `/` for special schemes (`http`, `https`, `ws`, `wss`, `ftp`, `file`), so the two parsers extract different hosts from the same input string.\n\nFor example, `http://evil.com\\@allowed.com` is treated by `fast-uri` as host `allowed.com` with userinfo `evil.com\\`, while Node's WHATWG URL parser and `fetch()` see host `evil.com` with path `/@allowed.com`.\n\nApplications that use `fast-uri` to enforce host-based policy (allowlists, denylists, loopback/SSRF filtering, redirect validation, outbound proxy routing) before passing the same URL into Node's URL or `fetch()` consumers see a policy/use desync and can be steered to an unintended destination, including cloud metadata endpoints, loopback, or internal hosts.\n\n### Patches\n\nUpgrade to `fast-uri` v4.1.1, v3.1.4, or v2.4.3.\n\n### Workarounds\n\nNone. Upgrade to the patched version.","status":"published","published":"2026-07-21T22:08:28Z","modified":"2026-07-21T22:08:29Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","level":"high"}],"cwes":["CWE-436"],"updated_at":"2026-11-02T14:40:50.444681Z"}],"nvd":[{"id":"CVE-2026-16221","description":"Impact: fast-uri versions from 2.3.1 through 4.1.0 (including the 3.x line up to 3.1.3 and the 2.x line up to 2.4.2) do not treat a literal backslash character (U+005C) as an authority delimiter. Node's native WHATWG URL parser, used by fetch, undici, and Node's http and https clients, normalizes the backslash to a forward slash for special schemes such as http, https, ws, wss, ftp, and file. As a result, the two parsers extract different hosts from the same input string. Applications that use fast-uri to enforce host-based policy such as allowlists, denylists, loopback or SSRF filtering, redirect validation, or outbound proxy routing before passing the same URL into Node's URL or fetch consumers can be steered to an unintended destination, including cloud metadata endpoints, loopback, or internal hosts. \n\nPatches: upgrade to fast-uri 4.1.1, 3.1.4, or 2.4.3.\n\nWorkarounds: none.","status":"published","published":"2026-07-19T15:16:49.027Z","modified":"2026-08-05T19:46:09.89Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","level":"high","assessor":"secondary"}],"cwes":["CWE-436"],"updated_at":"2026-11-02T14:12:30.631352Z"}],"osv":[{"id":"CVE-2026-16221","title":"fast-uri vulnerable to host confusion via literal backslash authority delimiter","description":"Impact: fast-uri versions from 2.3.1 through 4.1.0 (including the 3.x line up to 3.1.3 and the 2.x line up to 2.4.2) do not treat a literal backslash character (U+005C) as an authority delimiter. Node's native WHATWG URL parser, used by fetch, undici, and Node's http and https clients, normalizes the backslash to a forward slash for special schemes such as http, https, ws, wss, ftp, and file. As a result, the two parsers extract different hosts from the same input string. Applications that use fast-uri to enforce host-based policy such as allowlists, denylists, loopback or SSRF filtering, redirect validation, or outbound proxy routing before passing the same URL into Node's URL or fetch consumers can be steered to an unintended destination, including cloud metadata endpoints, loopback, or internal hosts. \n\nPatches: upgrade to fast-uri 4.1.1, 3.1.4, or 2.4.3.\n\nWorkarounds: none.","status":"published","published":"2026-07-19T14:08:32.993Z","modified":"2026-10-28T02:30:45.288691315Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","level":"high"}],"cwes":["CWE-436"],"updated_at":"2026-11-02T15:44:57.682091Z"},{"id":"DEBIAN-CVE-2026-16221","description":"Impact: fast-uri versions from 2.3.1 through 4.1.0 (including the 3.x line up to 3.1.3 and the 2.x line up to 2.4.2) do not treat a literal backslash character (U+005C) as an authority delimiter. Node's native WHATWG URL parser, used by fetch, undici, and Node's http and https clients, normalizes the backslash to a forward slash for special schemes such as http, https, ws, wss, ftp, and file. As a result, the two parsers extract different hosts from the same input string. Applications that use fast-uri to enforce host-based policy such as allowlists, denylists, loopback or SSRF filtering, redirect validation, or outbound proxy routing before passing the same URL into Node's URL or fetch consumers can be steered to an unintended destination, including cloud metadata endpoints, loopback, or internal hosts.   Patches: upgrade to fast-uri 4.1.1, 3.1.4, or 2.4.3.  Workarounds: none.","status":"published","published":"2026-07-19T15:16:49.027Z","modified":"2026-10-01T03:02:26.545181864Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","level":"high"}],"updated_at":"2026-11-02T15:45:52.562592Z"},{"id":"GHSA-v2hh-gcrm-f6hx","title":"fast-uri vulnerable to host confusion via literal backslash authority delimiter","description":"### Impact\n\n`fast-uri` v4.1.0 and earlier do not treat a literal backslash (U+005C) as an authority delimiter. Node's native WHATWG `URL` (used by `fetch()`, `undici`, and Node's `http`/`https` clients) normalizes `\\` to `/` for special schemes (`http`, `https`, `ws`, `wss`, `ftp`, `file`), so the two parsers extract different hosts from the same input string.\n\nFor example, `http://evil.com\\@allowed.com` is treated by `fast-uri` as host `allowed.com` with userinfo `evil.com\\`, while Node's WHATWG URL parser and `fetch()` see host `evil.com` with path `/@allowed.com`.\n\nApplications that use `fast-uri` to enforce host-based policy (allowlists, denylists, loopback/SSRF filtering, redirect validation, outbound proxy routing) before passing the same URL into Node's URL or `fetch()` consumers see a policy/use desync and can be steered to an unintended destination, including cloud metadata endpoints, loopback, or internal hosts.\n\n### Patches\n\nUpgrade to `fast-uri` v4.1.1, v3.1.4, or v2.4.3.\n\n### Workarounds\n\nNone. Upgrade to the patched version.","status":"published","published":"2026-07-21T22:08:28Z","modified":"2026-09-10T03:51:12.051886648Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","level":"high"}],"cwes":["CWE-436"],"updated_at":"2026-11-02T15:46:56.639206Z"},{"id":"RHSA-2026:54517","title":"Red Hat Security Advisory: Red Hat Hardened Images RPMs Security Update","status":"published","published":"2026-08-13T10:17:50Z","modified":"2026-10-20T10:11:09Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"updated_at":"2026-11-02T15:53:21.457353Z"},{"id":"RHSA-2026:54518","title":"Red Hat Security Advisory: Red Hat Hardened Images RPMs Security Update","status":"published","published":"2026-08-14T10:16:47Z","modified":"2026-10-20T10:11:09Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"updated_at":"2026-11-02T15:53:21.457353Z"},{"id":"UBUNTU-CVE-2026-16221","description":"Impact: fast-uri versions from 2.3.1 through 4.1.0 (including the 3.x line up to 3.1.3 and the 2.x line up to 2.4.2) do not treat a literal backslash character (U+005C) as an authority delimiter. Node's native WHATWG URL parser, used by fetch, undici, and Node's http and https clients, normalizes the backslash to a forward slash for special schemes such as http, https, ws, wss, ftp, and file. As a result, the two parsers extract different hosts from the same input string. Applications that use fast-uri to enforce host-based policy such as allowlists, denylists, loopback or SSRF filtering, redirect validation, or outbound proxy routing before passing the same URL into Node's URL or fetch consumers can be steered to an unintended destination, including cloud metadata endpoints, loopback, or internal hosts. Patches: upgrade to fast-uri 4.1.1, 3.1.4, or 2.4.3. Workarounds: none.","status":"published","published":"2026-07-19T15:16:00Z","modified":"2026-10-17T12:59:53.973833171Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","level":"high"}],"updated_at":"2026-11-02T16:56:00.592716Z"},{"id":"CLSA-2026-1784682957","title":"TuxCare security update for fast-uri (2 CVEs)","description":"TuxCare rebuilt fast-uri to address 2 CVEs. Fixed in 3.0.3-tuxcare.2.","status":"published","published":"2026-08-04T14:52:46Z","modified":"2026-10-15T09:47:54.075457056Z","updated_at":"2026-11-02T15:43:46.482572Z"},{"id":"CLSA-2026-1784769538","title":"TuxCare security update for fast-uri (1 CVE)","description":"TuxCare rebuilt fast-uri to address 1 CVE. Fixed in 3.0.1-tuxcare.2.","status":"published","published":"2026-08-04T14:52:47Z","modified":"2026-10-15T09:47:36.759573076Z","updated_at":"2026-11-02T15:43:46.482572Z"},{"id":"CLSA-2026-1784769612","title":"TuxCare security update for fast-uri (6 CVEs)","description":"TuxCare rebuilt fast-uri to address 6 CVEs. Fixed in 2.4.2-tuxcare.1.","status":"published","published":"2026-08-04T14:52:48Z","modified":"2026-10-15T09:47:36.429669264Z","updated_at":"2026-11-02T15:43:46.482572Z"},{"id":"CLSA-2026-1790893546","title":"TuxCare security update for fast-uri (1 CVE)","description":"TuxCare rebuilt fast-uri to address 1 CVE. Fixed in 3.1.2-tuxcare.3.","status":"published","published":"2026-10-01T22:25:46Z","modified":"2026-10-15T09:47:57.816655081Z","updated_at":"2026-11-02T15:43:48.65893Z"},{"id":"CLSA-2026-1791370091","title":"TuxCare security update for fast-uri (1 CVE)","description":"TuxCare rebuilt fast-uri to address 1 CVE. Fixed in 3.1.3-tuxcare.5.","status":"published","published":"2026-10-07T10:48:11Z","modified":"2026-10-15T09:47:39.579300362Z","updated_at":"2026-11-02T15:43:49.016976Z"},{"id":"CLSA-2026-1791814871","title":"TuxCare security update for fast-uri (5 CVEs)","description":"TuxCare rebuilt fast-uri to address 5 CVEs. Fixed in 3.1.0-tuxcare.3.","status":"published","published":"2026-10-12T14:21:11Z","modified":"2026-10-15T09:47:40.140546262Z","updated_at":"2026-11-02T15:43:50.599064Z"},{"id":"CLSA-2026-1792143884","title":"TuxCare security update for fast-uri (7 CVEs)","description":"TuxCare rebuilt fast-uri to address 7 CVEs. Fixed in 3.0.6-tuxcare.2.","status":"published","published":"2026-10-16T09:44:44Z","modified":"2026-10-16T12:15:03.199589181Z","updated_at":"2026-11-02T15:43:50.949147Z"},{"id":"ROOT-APP-NPM-CVE-2026-16221","title":"CVE-2026-16221 in fast-uri - Patched by Root","description":"Root has patched CVE-2026-16221 in the fast-uri package for Root:npm. Multiple fixed versions available.","status":"published","published":"2026-11-05T10:50:51Z","modified":"2026-11-05T11:15:09.72755169Z","updated_at":"2026-11-05T13:30:49.23793Z"}]}}