cvedb.io
CVE-2026-4867
HIGH · CVSS 7.5
EPSS exploitation probability: 0%
Published 2026-03-26T17:16:42.983 · Last modified 2026-06-17T10:57:21.827

Summary

Impact: A bad regular expression is generated any time you have three or more parameters within a single segment, separated by something that is not a period (.). For example, /:a-:b-:c or /:a-:b-:c-:d. The backtrack protection added in [email protected] only prevents ambiguity for two parameters. With three or more, the generated lookahead does not block single separator characters, so capture groups overlap and cause catastrophic backtracking. Patches: Upgrade to [email protected] Custom regex patterns in route definitions (e.g., /:a-:b([^-/]+)-:c([^-/]+)) are not affected because they override the default capture group. Workarounds: All versions can be patched by providing a custom regular expression for parameters after the first in a single segment. As long as the custom

Affected products

pillarjs — path-to-regexp

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References

This product uses data from the NVD API but is not endorsed or certified by the NVD. Informational only; not professional security advice.