NIST deprecates RSA-2048 from 2030. Find every one of them before attackers do.
📦
📦 npm
Not in CISA KEV
HIGH severity

CVE-2026-4926 — path-to-regexp

HIGH

CVE-2026-4926 is a high-severity (CVSS 7.5) Uncontrolled Resource Consumption vulnerability in path-to-regexp. A fix is available for path-to-regexp — see the affected versions and patch details below.

path-to-regexp vulnerable to Denial of Service via sequential optional groups

Also known asGHSA-j3q9-mxjg-w52f
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 1, 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-2026-4926.

EPSS Exploitation Probability

via FIRST.org ↗
0.8%probability of exploitation in next 30 days
Lower Risk-0.09%
Lower risk than most CVEs57th percentile — riskier than 57% of all scored CVEsHighest risk
0.00%0.46%0.93%1.39%0.1%0.8%May 26Aug 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
314.1Mdownloads / week

Description

Impact

A bad regular expression is generated any time you have multiple sequential optional groups (curly brace syntax), such as {a}{b}{c}:z. The generated regex grows exponentially with the number of groups, causing denial of service.

Patches

Fixed in version 8.4.0.

Workarounds

Limit the number of sequential optional groups in route patterns. Avoid passing user-controlled input as route patterns.

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 CVE-2026-4926 is resolved across your whole dependency graph.

  3. Workarounds

    Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

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 is an Important flaw in `path-to-regexp` that can lead to a Denial of Service. The vulnerability occurs when specially crafted input containing multiple sequential optional groups is used to generate regular expressions, causing exponential resource consumption. The Red Hat Advanced Cluster Security is not…

Workaround published by Red Hat
To mitigate this vulnerability, limit the use of multiple sequential optional groups in route patterns within applications that use `path-to-regexp`. Additionally, avoid directly passing user-controlled input as route patterns to prevent the generation of maliciously crafted regular expressions.
Source: Red Hat security advisory for CVE-2026-4926 (CC BY 4.0)
ProductFixed inAdvisory
Cryostat 4 on RHEL 9cryostat/cryostat-openshift-console-plugin-rhel9:4.2.0-9RHSA-2026:17789
Red Hat Ansible Automation Platform 2.5 for RHEL 8automation-gateway-0:2.5.20260422-3.el8apRHSA-2026:24761
Red Hat Ansible Automation Platform 2.6 for RHEL 9automation-platform-ui-0:2.6.9-1.el9apRHSA-2026:24762
Migration Toolkit for Virtualization 2.10migration-toolkit-virtualization/mtv-console-plugin-rhel9:1779139872RHSA-2026:19409
Migration Toolkit for Virtualization 2.9migration-toolkit-virtualization/mtv-console-plugin-rhel9:1778927462RHSA-2026:19410
Red Hat Ansible Automation Platform 2.6ansible-automation-platform-tech-preview/mcp-server-rhel9:1777386606RHSA-2026:13545
Red Hat Ansible Automation Platform 2.6ansible-automation-platform-26/gateway-rhel9:1779773804RHSA-2026:24866
Red Hat Developer Hub 1.8rhdh/rhdh-hub-rhel9:1776784286RHSA-2026:9742

Frequently Asked Questions

### Impact A bad regular expression is generated any time you have multiple sequential optional groups (curly brace syntax), such as `{a}{b}{c}:z`. The generated regex grows exponentially with the number of groups, causing denial of service. ### Patches Fixed in version 8.4.0. ### Workarounds Limit the number of sequential optional groups in route patterns. Avoid passing user-controlled input as route patterns.
O3 Security · Impact-Aware SCA

Is CVE-2026-4926 in your dependencies?

Find it across npm, including transitive dependencies.

Scan my dependencies How O3 SCA works
CVE-2026-4926: path-to-regexp DoS — Fixed in 8.4.0