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.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| path-to-regexp | path-to-regexp | unaffected |
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Subscriptions
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Tracking
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Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
| Link | Providers |
|---|---|
| https://cna.openjsf.org/security-advisories.html |
|
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
|
MITRE
Status: PUBLISHED
Assigner: openjs
Published:
Updated: 2026-03-26T18:59:38.000Z
Reserved: 2026-03-26T18:36:49.229Z
Link: CVE-2026-4926
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-03-26T19:17:08.387
Modified: 2026-03-26T19:17:08.387
Link: CVE-2026-4926
Redhat
No data.
OpenCVE Enrichment
No data.