CVE-2022-21680: 
JavaScript vulnerability analysis and mitigation

The vulnerability (CVE-2022-21680) was discovered in the marked library, affecting versions prior to 4.0.10. The issue involves a regular expression pattern in block.def that may cause catastrophic backtracking against certain strings, leading to a regular expression denial of service (ReDoS) vulnerability. The vulnerability was disclosed on January 14, 2022 (GitHub Advisory).

The vulnerability exists in the regular expression pattern block.def within the marked library. When processing certain input strings, the pattern can trigger catastrophic backtracking, causing excessive CPU usage. A proof of concept demonstrates this by using repeated spaces: [x]:${' '.repeat(1500)}x ${' '.repeat(1500)} x (GitHub Advisory). The vulnerability has been assigned a CVSS v3 base score of 7.5 (High), with attack vector: Network, attack complexity: Low, privileges required: None, user interaction: None, scope: Unchanged, and availability impact: High (GitHub Advisory).

The vulnerability can lead to denial of service conditions when processing untrusted markdown through the marked library. When exploited, it can cause excessive CPU usage, potentially affecting the availability of the system processing the markdown content (GitHub Advisory).

The vulnerability has been patched in version 4.0.10 of the marked library. Users are advised to upgrade to this version or later. As a workaround, users can either avoid running untrusted markdown through marked or run marked on a worker thread with a reasonable time limit to prevent resource drainage (GitHub Advisory).