CVE-2022-29181 is a high-severity vulnerability affecting Nokogiri, an open-source XML and HTML parsing library widely used in Ruby applications. The vulnerability arises from improper handling of unexpected data types in Nokogiri versions prior to 1.13.6, specifically within the XML and HTML4 SAX parsers. Nokogiri does not perform adequate type checking on inputs, which allows specially crafted untrusted inputs that are not strictly strings to cause illegal memory access errors such as segmentation faults or reads from unrelated memory regions. This behavior can lead to application crashes (denial of service) or potentially expose sensitive memory contents, impacting confidentiality. The root cause is classified under CWE-241: Improper Handling of Unexpected Data Type. The vulnerability has a CVSS 3.1 base score of 8.2, indicating high severity, with an attack vector of network (remote exploitation possible), low attack complexity, no privileges required, and no user interaction needed. The scope is unchanged, and the impact affects confidentiality (partial loss) and availability (complete loss), but not integrity. The issue was patched in Nokogiri version 1.13.6 by enforcing proper type checking. As a workaround, developers can ensure untrusted inputs are converted to strings (e.g., by calling #to_s) before parsing. No known exploits are reported in the wild as of the publication date, but the vulnerability's characteristics make it a significant risk for applications processing untrusted XML/HTML data. Given Nokogiri's popularity in Ruby-based web applications and services, this vulnerability could be leveraged remotely to cause denial of service or information disclosure if exploited.

For European organizations, the impact of CVE-2022-29181 can be substantial, especially for those relying on Ruby applications that use Nokogiri for XML or HTML parsing. The vulnerability can lead to application crashes, causing denial of service and potential disruption of critical services, which may affect business continuity and availability of web services. Additionally, the possibility of reading unrelated memory could expose sensitive data, leading to confidentiality breaches. Sectors such as finance, healthcare, government, and e-commerce, which often process untrusted XML/HTML inputs from external sources, are particularly at risk. The disruption or data leakage could result in regulatory non-compliance under GDPR, leading to legal and financial penalties. Moreover, the ease of exploitation without authentication or user interaction increases the threat level, making automated attacks feasible. Although no known exploits are currently reported, the vulnerability's presence in a widely used library means that attackers could develop exploits targeting vulnerable European organizations, especially those with internet-facing Ruby applications.

European organizations should prioritize upgrading Nokogiri to version 1.13.6 or later to apply the official patch that enforces proper input type checking. Until upgrades can be completed, developers should implement input validation by explicitly converting all untrusted inputs to strings using methods like #to_s before passing them to Nokogiri parsers. Additionally, organizations should audit their Ruby applications to identify any use of Nokogiri and assess exposure to untrusted XML/HTML inputs. Implementing runtime application self-protection (RASP) or web application firewalls (WAFs) with rules to detect and block malformed XML/HTML payloads can provide additional defense layers. Monitoring application logs for segmentation faults or crashes related to Nokogiri parsing can help detect exploitation attempts. Finally, organizations should incorporate this vulnerability into their vulnerability management and patching processes, ensuring timely updates and testing to prevent exploitation.