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.
Analysis and contextual insights are available on OpenCVE Cloud.
No vendor fix or workaround currently provided.
Additional remediation guidance may be available on OpenCVE Cloud.
Tracking
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| Source | ID | Title |
|---|---|---|
Github GHSA |
GHSA-j3q9-mxjg-w52f | path-to-regexp vulnerable to Denial of Service via sequential optional groups |
Thu, 16 Apr 2026 18:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Pillarjs
Pillarjs path-to-regexp |
|
| CPEs | cpe:2.3:a:pillarjs:path-to-regexp:*:*:*:*:*:node.js:*:* | |
| Vendors & Products |
Pillarjs
Pillarjs path-to-regexp |
Sat, 28 Mar 2026 17:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
ssvc
|
Sat, 28 Mar 2026 12:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| References |
| |
| Metrics |
threat_severity
|
threat_severity
|
Fri, 27 Mar 2026 08:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Path-to-regexp
Path-to-regexp path-to-regexp |
|
| Vendors & Products |
Path-to-regexp
Path-to-regexp path-to-regexp |
Thu, 26 Mar 2026 19:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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. | |
| Title | path-to-regexp vulnerable to Denial of Service via sequential optional groups | |
| Weaknesses | CWE-1333 CWE-400 |
|
| References |
| |
| Metrics |
cvssV3_1
|
Status: PUBLISHED
Assigner: openjs
Published:
Updated: 2026-03-27T19:44:53.294Z
Reserved: 2026-03-26T18:36:49.229Z
Link: CVE-2026-4926
Updated: 2026-03-27T19:44:50.233Z
Status : Analyzed
Published: 2026-03-26T19:17:08.387
Modified: 2026-04-16T18:04:13.123
Link: CVE-2026-4926
OpenCVE Enrichment
Updated: 2026-03-27T09:25:40Z
Github GHSA