GHSA-jqff-g426-hqxp

Suggest an improvement
Source
https://github.com/advisories/GHSA-jqff-g426-hqxp
Import Source
https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/09/GHSA-jqff-g426-hqxp/GHSA-jqff-g426-hqxp.json
JSON Data
https://api.osv.dev/v1/vulns/GHSA-jqff-g426-hqxp
Aliases
Downstream
Published
2026-09-02T15:41:53Z
Modified
2026-09-10T03:50:54Z
Severity
  • 7.5 (High) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N CVSS Calculator
Summary
fast-uri vulnerable to host confusion via percent-encoded scheme normalization
Details

Impact

fast-uri decodes percent-encoded characters in the scheme component with the legacy global unescape() and serializes the result back as raw characters, without re-escaping it or validating it as a scheme. A scheme that decodes to characters outside the RFC 3986 scheme grammar can therefore introduce structure the original input did not contain.

For example, %2f%2fevil.example:/pwn parses with no authority (parse().host is undefined), but resolve() and normalize() return //evil.example:/pwn, which reparses with host evil.example. The %uXXXX form (%u002f%u002fevil.example:/pwn) produces the same result, and a scheme containing %0d%0a reaches the output as a raw CR LF.

Applications that normalize or resolve untrusted URLs before a redirect check, host allowlist, or outbound request decision, especially ones that treat a missing authority as same-origin, can be steered to an attacker-chosen authority, and a normalized URI placed in a response header can carry an injected CR LF.

Patches

Upgrade to fast-uri >= 4.1.3, or >= 3.1.6 in the v3.x release line, or >= 2.4.5 in the v2.x release line.

Workarounds

None. Upgrade to the patched version.

Database specific 
{
    "cwe_ids": [
        "CWE-177"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-09-02T15:41:53Z",
    "nvd_published_at": "2026-08-24T11:16:40Z",
    "severity": "HIGH"
}
References

Affected packages

npm / fast-uri

Package

Name
fast-uri
View open source insights on deps.dev
Purl
pkg:npm/fast-uri

Affected ranges

Type
SEMVER
Events
Introduced
2.3.1
Fixed
2.4.5

Database specific

source 
"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/09/GHSA-jqff-g426-hqxp/GHSA-jqff-g426-hqxp.json"

npm / fast-uri

Package

Name
fast-uri
View open source insights on deps.dev
Purl
pkg:npm/fast-uri

Affected ranges

Type
SEMVER
Events
Introduced
3.0.0
Fixed
3.1.6

Database specific

source 
"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/09/GHSA-jqff-g426-hqxp/GHSA-jqff-g426-hqxp.json"

npm / fast-uri

Package

Name
fast-uri
View open source insights on deps.dev
Purl
pkg:npm/fast-uri

Affected ranges

Type
SEMVER
Events
Introduced
4.0.0
Fixed
4.1.3

Database specific

source 
"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/09/GHSA-jqff-g426-hqxp/GHSA-jqff-g426-hqxp.json"