GHSA-v2hh-gcrm-f6hx
Dashboard / Vulnerabilities / GHSA-v2hh-gcrm-f6hx
Summary: fast-uri vulnerable to host confusion via literal backslash authority delimiter
Details: ### Impact `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. For 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`. Applications 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. ### Patches Upgrade to `fast-uri` v4.1.1, v3.1.4, or v2.4.3. ### Workarounds None. Upgrade to the patched version.
References: https://github.com/fastify/fast-uri/security/advisories/GHSA-v2hh-gcrm-f6hx, https://nvd.nist.gov/vuln/detail/CVE-2026-16221, https://github.com/fastify/fast-uri/commit/0542a216860fd70c062a4730e620576f62ded057, https://github.com/fastify/fast-uri/commit/2d50fbabc80e4d0884fe0f6a98fe118ce6faa353, https://github.com/fastify/fast-uri/commit/9438266d6a7ded688c8bc7c4ba506da17f44a17b, https://cna.openjsf.org/security-advisories.html, https://github.com/fastify/fast-uri, https://github.com/fastify/fast-uri/releases/tag/v2.4.3, https://github.com/fastify/fast-uri/releases/tag/v3.1.4, https://github.com/fastify/fast-uri/releases/tag/v4.1.1
Affected packages
Package
Name: fast-uri
Purl: pkg:npm/fast-uri
Affected ranges
Type: SEMVER
Events:
