GitHub Advisoryadvisory · npm

GHSA-v39h-62p7-jpjc fast-uri vulnerable to host confusion via percent-encoded authority delimiters

HIGH Published 2026-05-08 Modified 2026-09-01 Official page ↗
Aliases
CVE-2026-6322
Ecosystem
npm
Packages
fast-uri
Severity
High
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Weaknesses
CWE-140, CWE-436
Reviewed
2026-05-08

Affected packages

• npm fast-uri: >= 3.0.0, < 3.1.2 → fixed in 3.1.2 • npm fast-uri: < 2.4.1 → fixed in 2.4.1

Description

Impact `fast-uri` v3.1.1 and earlier decodes percent-encoded authority delimiters (`%40` as `@`, `%3A` as `:`) inside the host component and serializes them back as raw characters. This changes the URI structure, turning a hostname into userinfo plus a different host. For example, `http://trusted.com%40evil.com/` normalizes to `http://[email protected]/`, which reparses as host `evil.com` with userinfo `trusted.com`. Applications that normalize untrusted URLs before host allowlist checks, redirect validation, or outbound request routing can be steered to a different authority than the original URL appeared to contain. Patches Upgrade to `fast-uri` >= 3.1.2, or if you are in the v2.x release line, v2.4.1 Workarounds None. Upgrade to the patched version.

Related

Alias · CVE (1)

  • CVE-2026-6322 fast-uri normalize() decoded percent-encoded authority delimiters inside the host component and then re-emitted them as raw delimiters… vulnerability

Weakness · CWE (2)

  • CWE-140 Improper Neutralization of Delimiters weakness
  • CWE-436 Interpretation Conflict weakness

References