{"schema_version":"1.9.0","id":"GHSA-4c8g-83qw-93j6","published":"2026-07-21T19:03:11Z","modified":"2026-09-04T15:45:22.131031223Z","aliases":["CVE-2026-13676"],"related":["CGA-6q79-h986-qcpv"],"summary":"fast-uri vulnerable to host confusion via failed IDN canonicalization","details":"### Impact\n\n`fast-uri` versions `>= 2.3.1, <= 4.0.0` fail to canonicalize Unicode/IDN hostnames for HTTP-family URLs. The IDN conversion path calls `URL.domainToASCII(...)` on the global WHATWG `URL` constructor, where that helper does not exist. The resulting `TypeError` is silently routed into `parsed.error`, but `parse()`, `normalize()`, and `equal()` all return with the host left in its original Unicode form.\n\nFor example, `http://127。0。0。1/` is treated by `fast-uri` as host `127。0。0。1`, while Node's WHATWG URL parser and `fetch()` canonicalize the same input to `127.0.0.1`.\n\nApplications that use `fast-uri` to enforce host-based policy (denylists, loopback 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.\n\n### Patches\n\nUpgrade to `fast-uri` v4.0.1, v3.1.3, or v2.4.2\n\n### Workarounds\n\nNone. Upgrade to the patched version.","affected":[{"package":{"name":"fast-uri","ecosystem":"npm","purl":"pkg:npm/fast-uri"},"ranges":[{"type":"SEMVER","events":[{"introduced":"4.0.0"},{"fixed":"4.0.1"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-4c8g-83qw-93j6/GHSA-4c8g-83qw-93j6.json"}},{"package":{"name":"fast-uri","ecosystem":"npm","purl":"pkg:npm/fast-uri"},"ranges":[{"type":"SEMVER","events":[{"introduced":"3.0.0"},{"fixed":"3.1.3"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-4c8g-83qw-93j6/GHSA-4c8g-83qw-93j6.json"}},{"package":{"name":"fast-uri","ecosystem":"npm","purl":"pkg:npm/fast-uri"},"ranges":[{"type":"SEMVER","events":[{"introduced":"2.3.1"},{"fixed":"2.4.2"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-4c8g-83qw-93j6/GHSA-4c8g-83qw-93j6.json"}}],"references":[{"type":"WEB","url":"https://github.com/fastify/fast-uri/security/advisories/GHSA-4c8g-83qw-93j6"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-13676"},{"type":"WEB","url":"https://github.com/fastify/fast-uri/pull/188"},{"type":"WEB","url":"https://github.com/fastify/fast-uri/commit/2a6d357a18a68e6d812824379fd3388a1ae50d05"},{"type":"WEB","url":"https://github.com/fastify/fast-uri/commit/21ea1f9d70495c931f55dff893a8fa38f4f2e6bd"},{"type":"WEB","url":"https://github.com/fastify/fast-uri/commit/01db48010f594b98f7b323be18b393791c66ed1d"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:54760"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:56366"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:56431"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:57013"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:57191"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:57194"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:57590"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:59593"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:60386"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:60520"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:61314"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:63371"},{"type":"WEB","url":"https://access.redhat.com/security/cve/CVE-2026-13676"},{"type":"WEB","url":"https://bugzilla.redhat.com/show_bug.cgi?id=2494197"},{"type":"WEB","url":"https://cna.openjsf.org/security-advisories.html"},{"type":"PACKAGE","url":"https://github.com/fastify/fast-uri"},{"type":"WEB","url":"https://github.com/fastify/fast-uri/releases/tag/v2.4.2"},{"type":"WEB","url":"https://github.com/fastify/fast-uri/releases/tag/v3.1.3"},{"type":"WEB","url":"https://github.com/fastify/fast-uri/releases/tag/v4.0.1"},{"type":"WEB","url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-13676.json"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:37186"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:37585"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:37628"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:40118"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:40262"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:40765"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:40945"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:41066"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:41928"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:41929"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:42815"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:43038"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:44239"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:44268"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:47728"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:48124"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:48126"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:49642"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:50340"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:50479"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:50758"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:51196"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:51197"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:51342"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:51348"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:51349"}],"database_specific":{"cwe_ids":["CWE-436","CWE-551"],"github_reviewed":true,"github_reviewed_at":"2026-07-21T19:03:11Z","nvd_published_at":"2026-06-29T14:16:47Z","severity":"HIGH"},"severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N"}]}