This advisory has been withdrawn because it is a duplicate of GHSA-c4rq-3m3g-8wgx. This link is maintained to preserve external references.

Nokogiri versions before 1.19.3 contain regular expression denial of service vulnerabilities in the CSS selector tokenizer affecting string-literal and identifier tokenization. Attackers can inject adversarial CSS selectors into methods like Node#css, Node#at css, and Searchable#search to cause exponential regex backtracking and denial of service.