CVE-2026-4926
High
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.
SeverityHigh
CVSS7.5
Exploit probability—
ProductPillarjs Path-to-regexp
PublishedMar 26, 2026
First seenMar 26, 2026
How to fix
Update
- pillarjs path-to-regexp8.4.0 or later
- path-to-regexp8.4.0 or later
Vendor advisories
- access.redhat.com/errata/RHSA-2026:24761
- access.redhat.com/errata/RHSA-2026:24762
- 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-2026:24866
- access.redhat.com/errata/RHSA-2026:13545
- access.redhat.com/errata/RHSA-2026:9742
- access.redhat.com/errata/RHSA-2026:13826
- access.redhat.com/errata/RHSA-2026:36651
- access.redhat.com/errata/RHSA-2026:40945
- access.redhat.com/errata/RHSA-2026:40118
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| pillarjs path-to-regexp | 8.0.0 ≤ v < 8.4.0 | 8.4.0 |
| path-to-regexpnpm | 8.0.0 ≤ v < 8.4.0 | 8.4.0 |
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