jsx-slack is a package for building JSON objects for Slack block kit surfaces from JSX. The maintainers found the patch for CVE-2021-43838 in jsx-slack v4.5.1 is insufficient tfor protection from a Regular Expression Denial of Service (ReDoS) attack. If an attacker can put a lot of JSX elements into `<blockquote>` tag _with including multibyte characters_, an internal regular expression for escaping characters may consume an excessive amount of computing resources. v4.5.1 passes the test against ASCII characters but misses the case of multibyte characters. jsx-slack v4.5.2 has updated regular expressions for escaping blockquote characters to prevent catastrophic backtracking. It is also including an updated test case to confirm rendering multiple tags in `<blockquote>` with multibyte characters.

The package browserslist from 4.0.0 and before 4.16.5 are vulnerable to Regular Expression Denial of Service (ReDoS) during parsing of queries.

In JetBrains YouTrack before 2024.3.47707 potential ReDoS exploit was possible via email header parsing in Helpdesk functionality

An attacker can craft an input to the Parse functions that would be processed non-linearly with respect to its length, resulting in extremely slow parsing. This could cause a denial of service.