CVE-2024-45490 identifies a critical vulnerability in the libexpat XML parsing library, specifically in versions prior to 2.6.3. The issue arises from the xmlparse.c source file, where the XML_ParseBuffer function fails to reject negative length values. This improper input validation (classified under CWE-190: Integer Overflow or Wraparound) can lead to memory corruption, buffer overflows, or other undefined behaviors during XML parsing. Since libexpat is widely used in numerous applications and embedded systems for XML processing, this vulnerability presents a significant attack surface. The CVSS 3.1 base score of 9.8 reflects the high impact and ease of exploitation: the attack vector is network-based (AV:N), requires no privileges (PR:N), no user interaction (UI:N), and affects confidentiality, integrity, and availability (C:H/I:H/A:H). Exploitation could allow remote attackers to execute arbitrary code, cause denial of service, or leak sensitive information by crafting malicious XML data with negative length parameters. Although no exploits have been reported in the wild yet, the critical nature and widespread use of libexpat necessitate urgent attention from security teams. The absence of patch links suggests that fixes may be forthcoming or pending release, so organizations should monitor vendor advisories closely.

For European organizations, the impact of CVE-2024-45490 is substantial due to libexpat's pervasive use in software stacks, web services, and embedded devices. Successful exploitation could lead to remote code execution, enabling attackers to gain unauthorized access, disrupt services, or exfiltrate sensitive data. Critical infrastructure sectors such as telecommunications, finance, healthcare, and government services that rely on XML-based communication or data exchange are particularly vulnerable. The vulnerability's network accessibility and lack of required authentication increase the risk of widespread attacks, potentially affecting cloud services, enterprise applications, and IoT devices. Disruption or compromise of these systems could lead to operational downtime, financial losses, regulatory penalties under GDPR, and erosion of trust. The absence of known exploits currently provides a window for proactive mitigation, but the critical severity demands immediate risk assessment and remediation planning.

1. Monitor official libexpat repositories and vendor advisories for the release of version 2.6.3 or later that addresses this vulnerability, and apply patches promptly. 2. In the interim, restrict network access to services and applications that utilize libexpat for XML parsing, especially those exposed to untrusted inputs. 3. Implement input validation and filtering at application layers to detect and block XML payloads containing suspicious or malformed length parameters. 4. Employ runtime application self-protection (RASP) or intrusion detection systems (IDS) to monitor for anomalous XML parsing behavior indicative of exploitation attempts. 5. Conduct thorough inventory and risk assessments to identify all instances of libexpat usage within the organization’s software and embedded systems. 6. Where feasible, consider temporary mitigation by disabling or sandboxing XML parsing components until patches are applied. 7. Educate development and security teams about the vulnerability to ensure secure coding practices and prompt response to updates. 8. Collaborate with vendors and third-party providers to confirm their mitigation status and timelines.