CVE-2026-4923: path-to-regexp vulnerable to Regular Expression Denial of Service via multiple wildcards

March 27, 2026

When using multiple wildcards, combined with at least one parameter, a regular expression can be generated that is vulnerable to ReDoS. This backtracking vulnerability requires the second wildcard to be somewhere other than the end of the path.

Unsafe examples:

/*foo-*bar-:baz
/*a-:b-*c-:d
/x/*a-:b/*c/y

Safe examples:

/*foo-:bar
/*foo-:bar-*baz

References

cna.openjsf.org/security-advisories.html
github.com/advisories/GHSA-27v5-c462-wpq7
github.com/pillarjs/path-to-regexp
github.com/pillarjs/path-to-regexp/security/advisories/GHSA-27v5-c462-wpq7
makenowjust-labs.github.io/recheck/playground
nvd.nist.gov/vuln/detail/CVE-2026-4923

Code Behaviors & Features

Detect and mitigate CVE-2026-4923 with GitLab Dependency Scanning

Secure your software supply chain by verifying that all open source dependencies used in your projects contain no disclosed vulnerabilities. Dependency Scanning using SBOM also detects vulnerabilities from proprietary advisories that this site does not include. Learn more about Dependency Scanning using SBOM →