v8n is a javascript validation library. Versions of v8n prior to 1.5.1 were found to have an inefficient regular expression complexity in the `lowercase()` and `uppercase()` regex which could lead to a denial of service attack. In testing of the `lowercase()` function a payload of 'a' + 'a'.repeat(i) + 'A' with 32 leading characters took 29443 ms to execute. The same issue happens with uppercase(). Users are advised to upgrade. There are no known workarounds for this issue.

Affected: npm: v8n

### Impact Inefficient regular expression complexity of `lowercase()` and `uppercase()` regex could lead to a denial of service attack. With a formed payload `'a' + 'a'.repeat(i) + 'A'`, only 32 characters payload could take 29443 ms time execution when testing `lowercase()`. The same issue happens with `uppercase()`.

### Patches v1.5.1

### References [huntr.dev report](https://huntr.dev/bounties/2d92f644-593b-43b4-bfd1-c8042ac60609) [_Regular Expression Denial of Service (ReDoS) and Catastrophic Backtracking_](https://snyk.io/blog/redos-and-catastrophic-backtracking/)

### For more information If you have any questions or comments about this advisory: * Open an issue in [v8n issues list](https://github.com/imbrn/v8n) * Email us at [brunodev02221@gmail.com](mailto:brunodev02221@gmail.com)