CVE-2026-4926
March 26, 2026
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
path-to-regexp (NPM):
Affected version(s) >=8.0.0 <8.4.0Fix Suggestion:
Update to version 8.4.0path-to-regexp (NPM):
Affected version(s) >=8.0.0 <8.4.0Fix Suggestion:
Update to version 8.4.0path-to-regexp (NPM):
Affected version(s) >=8.0.0 <8.4.0Fix Suggestion:
Update to version 8.4.0Related Resources (4)
Do you need more information?
Contact UsCVSS v4
Base Score:
8.7
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
NONE
Vulnerable System Availability
HIGH
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
7.5
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Weakness Type (CWE)
EPSS
Base Score:
0.04
