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Vulnerability details

7.5/10
CVSS 3.1
GHSA-37ch-88jc-xwx2
not_affected Published 2026-03-27 Updated 2026-03-27
GitHub Advisory
Vulnerability Data from Dependency-Track
Affected versions
Score
7.5 CVSS 3.1 GITHUB CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Description
### 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 `path-to-regexp@0.1.12` 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 [path-to-regexp@0.1.13](https://github.com/pillarjs/path-to-regexp/releases/tag/v.0.1.13) 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 regular expression does not match the text before the parameter, you will be safe. For example, change `/:a-:b-:c` to `/:a-:b([^-/]+)-:c([^-/]+)`. If paths cannot be rewritten and versions cannot be upgraded, another alternative is to limit the URL length. ### References - [GHSA-9wv6-86v2-598j](https://github.com/advisories/GHSA-9wv6-86v2-598j) - [Detailed blog post: ReDoS the web](https://blakeembrey.com/posts/2024-09-web-redos/)
Same vulnerability as
CVE-2026-4867 not_affected according to EUVD-2026-16273
Analysis Read only
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