ZDF
Sign inSign up

Vulnerabilities

Vulnerability · CVE-2026-4926

Impact: A bad regular expression is generated any time you have multiple sequential optional groups (curly brace syntax), such as .

Published Mar 26, 2026 · catalog updated Sep 9, 2026 · Red Hat

Check if you run it

No confirmed exploitation is on record for CVE-2026-4926. EPSS is 0.89%. Act only if a listed version of Red Hat is installed.

Gaps on this record

  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High7.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.89%
Remediation
Advisory link
Affected products
cpe pillarjs/path-to-regexp

Impact: A bad regular expression is generated any time you have multiple sequential optional groups (curly brace syntax), such as . 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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe pillarjs/path-to-regexpversion unspecified

How to fix CVE-2026-4926

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-4926. EPSS is 0.89%. Act only if a listed version of Red Hat is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-1333: Inefficient Regular Expression Complexity; CWE-400: Uncontrolled Resource Consumption. EPSS 0.89%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Mar 26, 2026 · NIST NVD

    Detected

    Impact: A bad regular expression is generated any time you have multiple sequential optional groups (curly brace syntax), such as . 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.

  2. Sep 9, 2026 · NIST NVD

    Updated

    Impact: A bad regular expression is generated any time you have multiple sequential optional groups (curly brace syntax), such as . 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.

Sources

  • CSAF AdvisoriesVendor advisoryRHSA-2026:9742:CVE-2026-4926

    A flaw was found in path-to-regexp. A remote attacker could exploit this vulnerability by providing specially crafted input that generates a regular expression with multiple sequential optional groups. This leads to an exponential growth in the generated regular expression, causi

    security.access.redhat.com
  • CVE.orgVulnerability recordCVE-2026-4926

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-4926

    30-day exploitation probability 0.9%

    first.org
  • NIST NVDVulnerability recordCVE-2026-4926

    Impact: A bad regular expression is generated any time you have multiple sequential optional groups (curly brace syntax), such as . The generated regex grows exponentially with the number of groups, causing denial of service. Patches: Fixed in version 8.4.0. Work

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.