Nokogiri before 1.18.3 contains a stack buffer overflow vulnerability in libxml2 when reporting DTD validation errors with long QName prefixes, and a use-after-free vulnerability during validation against untrusted XML Schemas. Attackers can trigger these vulnerabilities by providing malicious DTD content or untrusted XSD files to cause denial of service or potential code execution.

Nokogiri before 1.15.6 and 1.16.x before 1.16.2 (CRuby, when using the packaged libxml2) is affected by a use-after-free vulnerability in libxml2 (CVE-2024-25062) in the xmlTextReader module, which underlies Nokogiri::XML::Reader. When using the XML Reader interface with DTD validation and XInclude expansion enabled, processing a crafted XML document can lead to an xmlValidatePopElement use-after-free. Nokogiri 1.15.6 and 1.16.2 resolve this by upgrading the packaged libxml2 to 2.11.7 and 2.12.5 respectively. JRuby and installations using system libxml2 are not affected.