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Vulnerability · Published Mar 26, 2026 · Assigned by openjs

CVE-2026-4926path-to-regexp vulnerable to Denial of Service via sequential optional groups

High 7.5

In plain English

A high-severity uncontrolled resource consumption in path-to-regexp from path-to-regexp. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.8% (higher than 57% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.5High
Exploit odds (30 days)0.8%top 43.1% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official 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 & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12node-path-to-regexpno fix listedDEBIAN-CVE-2026-4926
Debian:13node-path-to-regexpno fix listedDEBIAN-CVE-2026-4926
Debian:14node-path-to-regexp8.4.0-1DEBIAN-CVE-2026-4926
Ubuntu:22.04:LTSnode-path-to-regexpno fix listedUBUNTU-CVE-2026-4926
Ubuntu:24.04:LTSnode-path-to-regexpno fix listedUBUNTU-CVE-2026-4926
Ubuntu:25.10node-path-to-regexpno fix listedUBUNTU-CVE-2026-4926
Ubuntu:26.04:LTSnode-path-to-regexpno fix listedUBUNTU-CVE-2026-4926
npmpath-to-regexp8.4.0GHSA-j3q9-mxjg-w52f

Affected products (as reported)

VendorProductVersions
path-to-regexp path-to-regexp 8.0.0 – before 8.4.0

Weakness: CWE-400, CWE-1333 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References