Review reviewHigh

CVE-2026-4926

path-to-regexp path-to-regexp, Cryostat 4 on RHEL 9, Red Hat Ansible Automation Platform 2.5 for RHEL 8

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.

CVSS: 7.5
EPSS: 0.79%
CISA KEV: Not listed
Published: 2026.03.27

PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV

Exploit probability0.79%

Technical severityCVSS 7.5

Vulnerability overview

Affected product and versions

Product: path-to-regexp path-to-regexp, Cryostat 4 on RHEL 9, Red Hat Ansible Automation Platform 2.5 for RHEL 8
Affected versions: >= 8.0.0 < 8.4.0
Fixed versions: 8.4.0

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide

1
Identify
Confirm that path-to-regexp path-to-regexp, Cryostat 4 on RHEL 9, Red Hat Ansible Automation Platform 2.5 for RHEL 8 and an affected version are present.
2
Prioritize
Combine exploitation signals with asset exposure and business criticality.
3
Remediate
Follow the vendor advisory or supported update path and preserve rollback options.
4
Verify
Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CWE: CWE-1333, CWE-400