Login.

Vulnerability details

7.5/10
CVSS 3.1
GHSA-7p8r-x3mc-p8w7
resolved Published 2026-08-03 Updated 2026-08-03
GitHub Advisory
Vulnerability Data from Dependency-Track
Affected versions
Score
7.5 CVSS 3.1 GITHUB CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Description
### Impact `fast-uri` v4.1.1 and earlier require a literal `//` to recognize a URI authority, so a reference that uses `\\`, `/\`, or `\/` as the authority introducer (in place of `//`, after an optional scheme) is parsed with no authority: the sequence and everything after it fold into the path. Node's native WHATWG `URL` (used by `fetch()`, `undici`, and Node's `http`/`https` clients) instead treats `\` as interchangeable with `/` for special schemes (`http`, `https`, `ws`, `wss`, `ftp`, `file`), so the two parsers extract different hosts from the same input. For example, `fast-uri` resolves `\\evil.com/path` against base `https://allowed.com/` to `https://allowed.com/%5C%5Cevil.com/path` (confined to the trusted host), while Node's WHATWG URL resolves the same reference to `https://evil.com/path`. 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. ### Patches Upgrade to `fast-uri` v4.1.2, v3.1.5, v2.4.4. ### Workarounds None. Upgrade to the patched version.
Same vulnerability as
CVE-2026-18446 resolved according to EUVD-2026-51553
Analysis Read only
The analysis can only be edited by the BlueMind security teams: log in.

CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation. CVE data may be incomplete, delayed, or inaccurate. This website and all information provided are offered on an “as is” basis without warranties of any kind. This site is not affiliated with, endorsed by, or sponsored by the CVE Program or The MITRE Corporation.

This site uses data from the National Vulnerability Database (NVD), obtained through Dependency-Track, but is not endorsed or certified by the NVD or the National Institute of Standards and Technology (NIST). NVD data may be incomplete, delayed, or inaccurate.

CVSS (Common Vulnerability Scoring System) is owned and managed by FIRST.Org, Inc. and used by permission. The links on CVSS vectors open the FIRST CVSS calculators (CVSS 3.0, 3.1 and 4.0), or the NVD calculator for CVSS 2.0. This site is not affiliated with, endorsed by, or sponsored by FIRST.

GitHub is a trademark of GitHub, Inc. GHSA identifiers and advisory data come from the GitHub Advisory Database, licensed under CC-BY 4.0. GHSA data may be incomplete, delayed, or inaccurate. This site is not affiliated with, endorsed by, or sponsored by GitHub, Inc.

Source of the EUVD data: European Vulnerability Database (EUVD), © European Union Agency for Cybersecurity (ENISA), reused with acknowledgement of the source as provided by the ENISA legal notice and IPR policy. Changes: CVEManager does not display the EUVD records as such; it uses their aliases to link the CVE and GHSA identifiers designating the same vulnerability. EUVD data may be incomplete, delayed, or inaccurate. This site is not affiliated with, endorsed by, or sponsored by ENISA or the European Union.