MediumGHSA-27v5-c462-wpq7CVE-2026-4923

path-to-regexp vulnerable to Regular Expression Denial of Service via multiple wildcards

Published 27 Mar 2026 · Updated 10 Sept 2026

Affected package

Affected: >=8.0.0 <8.4.0
Fixed in: 8.4.0

Update to the fixed version for your release line, for example:npm install path-to-regexp@8.4.0

Details

Impact

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

Patches

Upgrade to version 8.4.0.

Workarounds

If developers are using multiple wildcard parameters, they can check the regex output with a tool such as https://makenowjust-labs.github.io/recheck/playground/ to confirm whether a path is vulnerable.

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References

Advisory data from OSV.dev (opens OSV.dev in a new tab), refreshed daily.