CVE-2026-4926
HIGHpath-to-regexp vulnerable to Denial of Service via sequential optional groups
Title source: cnaDescription
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 (1)
Scores
CVSS v3
7.5
EPSS
0.0006
EPSS Percentile
17.6%
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