CVE-2023-52425 is a denial of service (DoS) vulnerability affecting libexpat, a widely used XML parsing library, in versions through 2.5.0. The issue stems from the parser's handling of large tokens that require multiple buffer fills during parsing. Specifically, the parser performs many full reparsings of the input in such cases, leading to excessive CPU and memory consumption. This resource exhaustion can cause the affected application or service to become unresponsive or crash, resulting in a denial of service condition. The vulnerability does not affect confidentiality or integrity, as it does not allow code execution or data manipulation. The CVSS v3.1 base score is 7.5 (high), reflecting the network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), unchanged scope (S:U), no impact on confidentiality or integrity (C:N/I:N), and high impact on availability (A:H). No patches or exploits are currently publicly available, but the vulnerability is officially published and should be considered a significant risk for systems using libexpat for XML processing. The CWE classification is CWE-400 (Uncontrolled Resource Consumption).

For European organizations, this vulnerability poses a risk of service disruption in any application or infrastructure component that relies on libexpat for XML parsing. This includes web servers, middleware, cloud services, and embedded systems that process XML data. The denial of service can lead to downtime, degraded performance, and potential cascading failures in dependent systems. Industries such as finance, telecommunications, healthcare, and government, which often use XML for data interchange and configuration, may experience operational interruptions. The lack of confidentiality or integrity impact limits the risk to availability only, but availability is critical for business continuity and regulatory compliance in Europe. Additionally, the vulnerability can be exploited remotely without authentication or user interaction, increasing the attack surface. Although no active exploits are known, the widespread use of libexpat means that many organizations could be targeted once exploit code becomes available.

European organizations should proactively monitor libexpat releases and apply security patches as soon as they are published. In the absence of official patches, temporary mitigations include limiting the size and complexity of XML inputs accepted by applications, implementing input validation and rate limiting to prevent resource exhaustion, and isolating XML parsing processes to minimize impact on critical systems. Employing runtime resource monitoring and automated alerts for unusual CPU or memory usage can help detect exploitation attempts early. Where feasible, consider using alternative XML parsers that are not affected by this vulnerability. Security teams should also review their software supply chain to identify all components that embed libexpat and ensure they are updated accordingly. Network-level protections such as web application firewalls (WAFs) can be tuned to detect and block suspicious XML payloads that could trigger the vulnerability.