CVE-2022-22823 is a critical integer overflow vulnerability found in the build_model function within xmlparse.c of the Expat XML parsing library, specifically in versions prior to 2.4.3. Expat is a widely used open-source XML parser implemented in C, commonly embedded in many software products and systems for processing XML data. The vulnerability arises due to improper handling of integer values during XML parsing, leading to an integer overflow condition. This overflow can cause memory corruption, which attackers can exploit to achieve arbitrary code execution, denial of service, or other malicious outcomes. The vulnerability has a CVSS v3.1 base score of 9.8, indicating it is critical with network attack vector, no required privileges or user interaction, and impacts confidentiality, integrity, and availability severely. Although no known exploits are reported in the wild as of the published date, the severity and ease of exploitation make it a significant threat. The root cause is classified under CWE-190 (Integer Overflow or Wraparound), a common programming flaw where arithmetic operations exceed the maximum size of the data type, leading to unexpected behavior. Since Expat is embedded in numerous applications and platforms, the vulnerability potentially affects a broad range of software stacks that rely on XML parsing, including web servers, middleware, embedded systems, and enterprise applications. The absence of vendor or product specifics in the provided data suggests the need for organizations to audit their software dependencies to identify usage of vulnerable Expat versions and apply patches or mitigations accordingly.

For European organizations, the impact of CVE-2022-22823 can be substantial due to the widespread use of Expat in various software products and infrastructure components. Exploitation could lead to unauthorized code execution, allowing attackers to compromise sensitive data, disrupt critical services, or pivot within networks. This is particularly concerning for sectors such as finance, healthcare, government, and critical infrastructure, where XML processing is common and data confidentiality and availability are paramount. The vulnerability’s network attack vector and lack of required privileges mean attackers can exploit it remotely without authentication, increasing the risk of large-scale attacks or automated exploitation campaigns. Additionally, the potential for denial of service could disrupt business operations and service availability, impacting compliance with regulations like GDPR that mandate data protection and service continuity. The absence of known exploits in the wild does not diminish the urgency, as threat actors may develop exploits given the vulnerability’s critical nature. European organizations relying on software with embedded Expat versions prior to 2.4.3 should consider this vulnerability a high priority for remediation to prevent potential breaches and operational disruptions.

To mitigate CVE-2022-22823 effectively, European organizations should: 1) Conduct a thorough inventory of software and systems to identify any usage of Expat versions prior to 2.4.3. This includes checking dependencies in third-party applications, middleware, and embedded devices. 2) Apply patches or upgrade to Expat version 2.4.3 or later where available. If direct patching is not possible, coordinate with software vendors to obtain updates or mitigations. 3) Implement network-level protections such as Web Application Firewalls (WAFs) and Intrusion Detection/Prevention Systems (IDS/IPS) configured to detect and block malformed XML payloads or suspicious traffic patterns targeting XML parsers. 4) Employ strict input validation and sanitization for XML data processed by internal applications to reduce the risk of malicious payloads triggering the overflow. 5) Monitor security advisories and threat intelligence feeds for any emerging exploit attempts or proof-of-concept code related to this vulnerability. 6) Incorporate vulnerability scanning and static code analysis in the software development lifecycle to detect and remediate similar integer overflow issues proactively. 7) Establish incident response plans that include scenarios involving XML parser exploitation to ensure rapid containment and recovery if an attack occurs.