CVE-2026-4926
path-to-regexp vulnerable to Denial of Service via sequential optional groups
CVSS Score
7.5
EPSS Score
0.0%
EPSS Percentile
12th
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.
| CWE | CWE-400 CWE-1333 |
| Vendor | path-to-regexp |
| Product | path-to-regexp |
| Published | Mar 26, 2026 |
| Last Updated | Mar 27, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality
Integrity
Availability
Affected Versions
path-to-regexp / path-to-regexp
8.0.0 < 8.4.0
References
Credits
🔍 uug4na blakeembrey UlisesGascon