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Not in CISA KEV
HIGH severity

CVE-2026-6322 — fast-uri

HIGH

CVE-2026-6322 is a high-severity (CVSS 7.5) CWE-436 vulnerability in fast-uri. A fix is available for fast-uri — see the affected versions and patch details below.

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

Also known asGHSA-v39h-62p7-jpjc
Published
Updated
Affected
2 pkgs
Patched
2 / 2
Exploits
None indexed
Exploitation data as of Nov 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-6322.

EPSS Exploitation Probability

via FIRST.org ↗
0.5%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs44th percentile — riskier than 44% of all scored CVEsHighest risk
0.00%0.39%0.78%1.18%0.0%0.5%Jun 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

2 pkgs affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

354other npm packages depend on this — each one inherits the vulnerability until it's patched upstream
fast-urinpm
217.7Mdownloads / week

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.

Affected Packages

2 total 2 fixed
EcosystemPackageVulnerable rangeFix
📦npmfast-uri≥ 3.0.0&&< 3.1.23.1.2npm install fast-uri@3.1.2
📦npmfast-uriall versions2.4.1npm install fast-uri@2.4.1

Affected Products

1 product · 1 configurations
Application
fast-uriopenjsf
< 3.1.2
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for fast-uri, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update fast-uri to 3.1.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-6322 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatImportant

This Important flaw in the `fast-uri` library allows an attacker to bypass security controls in Red Hat products that process Uniform Resource Identifiers (URIs). By crafting a malicious URI with percent-encoded authority delimiters, an attacker can cause the library to incorrectly interpret the URI's authority,…

ProductFixed inAdvisory
Red Hat Ansible Automation Platform 2.5 for RHEL 8automation-gateway-0:2.5.20260715-1.el8apRHSA-2026:42078
Red Hat Ansible Automation Platform 2.6 for RHEL 9automation-platform-ui-0:2.6.10-1.el9apRHSA-2026:34160
Red Hat Data Grid 8.6.2fast-uriRHSA-2026:41951
Red Hat Enterprise Linux 10rh-podman-desktop-0:1.1.1-1.el10_2RHSA-2026:37385
Cluster Observability Operator 1.5cluster-observability-operator/distributed-tracing-console-plugin-pf4-rhel9:1782840519RHSA-2026:34342
multicluster engine for Kubernetes 2.11multicluster-engine/console-mce-rhel9:1780910888RHSA-2026:25271
Red Hat Advanced Cluster Management for Kubernetes 2.16rhacm2/console-rhel9:1780600823RHSA-2026:25273
Red Hat Ansible Automation Platform 2.6ansible-automation-platform-26/gateway-rhel9:1782761510RHSA-2026:34374

Frequently Asked Questions

### 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 th
O3 Security · Impact-Aware SCA

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CVE-2026-6322: fast-uri — Fixed in 3.1.2