CommonMarker versions prior to 0.23.4 are at risk of an integer overflow vulnerability. This vulnerability can result in possibly unauthenticated remote attackers to cause heap memory corruption, potentially leading to an information leak or remote code execution, via parsing tables with marker rows that contain more than UINT16_MAX columns.

Cross-site scripting (XSS) vulnerability in the PHP League CommonMark library before 0.18.3 allows remote attackers to insert unsafe links into HTML by using double-encoded HTML entities that are not properly escaped during rendering, a different vulnerability than CVE-2018-20583.

Cross-site scripting (XSS) vulnerability in the PHP League CommonMark library versions 0.15.6 through 0.18.x before 0.18.1 allows remote attackers to insert unsafe URLs into HTML (even if allow_unsafe_links is false) via a newline character (e.g., writing javascript as javascri%0apt).