CVE-2026-4926

HIGH7.5EPSS 0.02%

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

Published: 3/27/2026Modified: 3/30/2026

Also known as:GHSA-j3q9-mxjg-w52fCGA-4rwm-wmf3-xv3m

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 (2)

Debian/node-path-to-regexpfrom 0
npm/path-to-regexp>= 8.0.0, < 8.4.0

CVSS scores

Source	Version	Severity	Vector
osv	CVSS 3.1	HIGH7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References (5)

ADVISORYhttps://nvd.nist.gov/vuln/detail/CVE-2026-4926
ADVISORYhttps://security-tracker.debian.org/tracker/CVE-2026-4926
PATCHhttps://github.com/pillarjs/path-to-regexp
WEBhttps://cna.openjsf.org/security-advisories.html
WEBhttps://github.com/pillarjs/path-to-regexp/security/advisories/GHSA-j3q9-mxjg-w52f