CVE-2026-79770: Nokogiri versions before 1.19.3 contain regular expression denial of service vulnerabilities in the CSS selector tokeniz

Nokogiri versions before 1.19.3 have a ReDoS vulnerability (regular expression denial of service, where carefully crafted input causes a regex pattern to take exponentially longer to process) in how it parses CSS selectors. Attackers can exploit this by injecting malicious CSS selectors into methods like Node#css and Node#at_css to make the application hang or crash.