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High, CVSS 7.5amended

fast-uri vulnerable to host confusion via percent-encoded authority delimiters

CVE-2026-6322GHSA-v39h-62p7-jpjc

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (fast-uri 3.1.2, 2.4.1), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • npm fast-uri

    Affected
    >= 3.0.0, <= 3.1.1<= 2.4.0
    Fixed in
    2.4.1, 3.1.2

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
EPSS
  • CVE-2026-6322: 0.51% estimated exploitation activity in the next 30 days; percentile 43.71 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

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://trusted.com@evil.com/, 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.

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 2 · amended ·

    Amended from ghsa record GHSA-v39h-62p7-jpjc

  2. Revision 1 · created ·

    Published from osv record GHSA-v39h-62p7-jpjc

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-6322

Advisory: fast-uri vulnerable to host confusion via percent-encoded authority delimiters
IDs: CVE-2026-6322, GHSA-v39h-62p7-jpjc
Record: https://patchnext.com/advisories/cve-2026-6322 (revision 2, source checked 26 Oct 2026, 13:01 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: fast-uri 3.1.2, 2.4.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm fast-uri: affected >= 3.0.0, <= 3.1.1; <= 2.4.0; fixed in 2.4.1, 3.1.2

## Suggested inspection (read-only)
- `npm ls fast-uri --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on fast-uri.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-v39h-62p7-jpjc (OSV record GHSA-v39h-62p7-jpjc lists affected ranges: npm fast-uri >=3.0.0 =0 <2.4.1 (fixed))
- Verified: https://github.com/advisories/GHSA-v39h-62p7-jpjc (GitHub-reviewed advisory GHSA-v39h-62p7-jpjc lists affected ranges: npm fast-uri >=3.0.0 =0 <=2.4.0)

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