Description
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.
Recommendation
Update the path-to-regexp package to the latest compatible version. Followings are version details:
- Affected version(s): >= 8.0.0, < 8.4.0
- Patched version(s): 8.4.0
References
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See something that needs correcting? Let us knowUpdated March 27, 2026