GHSA-4c8g-83qw-93j6

Dashboard / Vulnerabilities / GHSA-4c8g-83qw-93j6

GHSA-4c8g-83qw-93j6

Summary: fast-uri vulnerable to host confusion via failed IDN canonicalization

Details: ### Impact `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. For 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`. Applications 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. ### Patches Upgrade to `fast-uri` v4.0.1, v3.1.3, or v2.4.2 ### Workarounds None. Upgrade to the patched version.

References: https://github.com/fastify/fast-uri/security/advisories/GHSA-4c8g-83qw-93j6, https://nvd.nist.gov/vuln/detail/CVE-2026-13676, https://github.com/fastify/fast-uri/pull/188, https://github.com/fastify/fast-uri/commit/2a6d357a18a68e6d812824379fd3388a1ae50d05, https://github.com/fastify/fast-uri/commit/21ea1f9d70495c931f55dff893a8fa38f4f2e6bd, https://github.com/fastify/fast-uri/commit/01db48010f594b98f7b323be18b393791c66ed1d, https://access.redhat.com/errata/RHSA-2026:54760, https://access.redhat.com/errata/RHSA-2026:56366, https://access.redhat.com/errata/RHSA-2026:56431, https://access.redhat.com/errata/RHSA-2026:57013, https://access.redhat.com/errata/RHSA-2026:57191, https://access.redhat.com/errata/RHSA-2026:57194, https://access.redhat.com/errata/RHSA-2026:57590, https://access.redhat.com/errata/RHSA-2026:59593, https://access.redhat.com/errata/RHSA-2026:60386, https://access.redhat.com/errata/RHSA-2026:60520, https://access.redhat.com/errata/RHSA-2026:61314, https://access.redhat.com/errata/RHSA-2026:63371, https://access.redhat.com/security/cve/CVE-2026-13676, https://bugzilla.redhat.com/show_bug.cgi?id=2494197, https://cna.openjsf.org/security-advisories.html, https://github.com/fastify/fast-uri, https://github.com/fastify/fast-uri/releases/tag/v2.4.2, https://github.com/fastify/fast-uri/releases/tag/v3.1.3, https://github.com/fastify/fast-uri/releases/tag/v4.0.1, https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-13676.json, https://access.redhat.com/errata/RHSA-2026:37186, https://access.redhat.com/errata/RHSA-2026:37585, https://access.redhat.com/errata/RHSA-2026:37628, https://access.redhat.com/errata/RHSA-2026:40118, https://access.redhat.com/errata/RHSA-2026:40262, https://access.redhat.com/errata/RHSA-2026:40765, https://access.redhat.com/errata/RHSA-2026:40945, https://access.redhat.com/errata/RHSA-2026:41066, https://access.redhat.com/errata/RHSA-2026:41928, https://access.redhat.com/errata/RHSA-2026:41929, https://access.redhat.com/errata/RHSA-2026:42815, https://access.redhat.com/errata/RHSA-2026:43038, https://access.redhat.com/errata/RHSA-2026:44239, https://access.redhat.com/errata/RHSA-2026:44268, https://access.redhat.com/errata/RHSA-2026:47728, https://access.redhat.com/errata/RHSA-2026:48124, https://access.redhat.com/errata/RHSA-2026:48126, https://access.redhat.com/errata/RHSA-2026:49642, https://access.redhat.com/errata/RHSA-2026:50340, https://access.redhat.com/errata/RHSA-2026:50479, https://access.redhat.com/errata/RHSA-2026:50758, https://access.redhat.com/errata/RHSA-2026:51196, https://access.redhat.com/errata/RHSA-2026:51197, https://access.redhat.com/errata/RHSA-2026:51342, https://access.redhat.com/errata/RHSA-2026:51348, https://access.redhat.com/errata/RHSA-2026:51349