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MEDIUM severity

path-to-regexp vulnerable to Regular Expression Denial of Service via multiple wildcardsGHSA-27v5-c462-wpq7

MEDIUM

GHSA-27v5-c462-wpq7 is a medium-severity (CVSS 5.9) CWE-1333 vulnerability in path-to-regexp. A fix is available for path-to-regexp — see the affected versions and patch details below.

Also known asCVE-2026-4923
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • 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 GHSA-27v5-c462-wpq7.

EPSS Exploitation Probability

via FIRST.org ↗
0.4%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs30th percentile — riskier than 30% of all scored CVEsHighest risk
0.00%0.29%0.58%0.87%0.1%0.4%0.4%0.4%0.4%May 26Oct 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

1 pkg 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.

7Kother npm packages depend on this — each one inherits the vulnerability until it's patched upstream
path-to-regexpnpm
316.1Mdownloads / week

Description

Impact

When using multiple wildcards, combined with at least one parameter, a regular expression can be generated that is vulnerable to ReDoS. This backtracking vulnerability requires the second wildcard to be somewhere other than the end of the path.

Unsafe examples:

/*foo-*bar-:baz
/*a-:b-*c-:d
/x/*a-:b/*c/y

Safe examples:

/*foo-:bar
/*foo-:bar-*baz

Patches

Upgrade to version 8.4.0.

Workarounds

If developers are using multiple wildcard parameters, they can check the regex output with a tool such as https://makenowjust-labs.github.io/recheck/playground/ to confirm whether a path is vulnerable.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
📦npmpath-to-regexp≥ 8.0.0&&< 8.4.08.4.0npm install path-to-regexp@8.4.0

Affected Products

1 product · 1 configurations
Application
path-to-regexppillarjs
≥ 8.0.0 && < 8.4.0
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 path-to-regexp, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update path-to-regexp to 8.4.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-27v5-c462-wpq7 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 HatModerate
Workaround published by Red Hat
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.
Source: Red Hat security advisory for GHSA-27v5-c462-wpq7 (CC BY 4.0)
ProductFixed inAdvisory
Red Hat Developer Hub 1.10rhdh/rhdh-hub-rhel9:1780930740RHSA-2026:24841

Frequently Asked Questions

### Impact When using multiple wildcards, combined with at least one parameter, a regular expression can be generated that is vulnerable to ReDoS. This backtracking vulnerability requires the second wildcard to be somewhere other than the end of the path. **Unsafe examples:** ``` /*foo-*bar-:baz /*a-:b-*c-:d /x/*a-:b/*c/y ``` **Safe examples:** ``` /*foo-:bar /*foo-:bar-*baz ``` ### Patches Upgrade to version `8.4.0`. ### Workarounds If developers are using multiple wildcard parameters, they can check the regex output with a tool such as https://makenowjust-labs.github.io/recheck/play
O3 Security · Impact-Aware SCA

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