path-to-regexp vulnerable to Denial of Service via sequential optional groups
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 software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | path-to-regexp | >= 8.0.0, < 8.4.0 | 8.4.0 |
References
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H- Weakness (CWE)
CWE-1333, CWE-400- Platform
- npm
- Package
path-to-regexp- Disclosed
- 27.03.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-j3q9-mxjg-w52f - CC BY 4.0
Vulnerability history: path-to-regexp
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 4
- First → latest
- 09.2024 03.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 3
- Medium 1
Disclosures per year
- 2024: 2
- 2025: 0
- 2026: 2
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path-to-regexp vulnerable to Denial of Service via sequential optional groups this entry
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