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.
Affected products
pillarjs: path-to-regexp
References10
- cna.openjsf.org/security-advisories.html Third Party Advisory
- access.redhat.com/errata/RHSA-2026:10153
- access.redhat.com/errata/RHSA-2026:10172
- access.redhat.com/errata/RHSA-2026:10175
- access.redhat.com/errata/RHSA-2026:13545
- access.redhat.com/errata/RHSA-2026:13826
- access.redhat.com/errata/RHSA-2026:17789
- access.redhat.com/errata/RHSA-2026:19409
- access.redhat.com/errata/RHSA-2026:19410
- access.redhat.com/errata/RHSA-2026:24761
Metrics
- CVSS 3.1
-
7.5
HIGH
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - EPSS — exploit probability
- 1% percentile: 58 · as of 12 November 2026
- CWE
- CWE-400CWE-1333
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