CVE-2026-4926

HIGH

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

Title source: cna
STIX 2.1

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.

References (20)

Core 20
Core References

Scores

CVSS v3 7.5
EPSS 0.0079
EPSS Percentile 52.7%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CISA SSVC

Vulnrichment
Exploitation none
Automatable yes
Technical Impact partial

Details

CWE
CWE-1333 CWE-400
Status published
Products (4)
npm/path-to-regexp 8.0.0 - 8.4.0npm
path-to-regexp/path-to-regexp 8.0.0 - 8.4.0
path-to-regexp/path-to-regexp 8.4.0
pillarjs/path-to-regexp 8.0.0 - 8.4.0
Published Mar 26, 2026
Tracked Since Mar 27, 2026