CVE-2025-59375 is a high-severity vulnerability identified in the libexpat XML parsing library, specifically in versions prior to 2.7.2. The vulnerability is classified under CWE-770, which pertains to the allocation of resources without limits or throttling. In this case, libexpat allows attackers to trigger excessively large dynamic memory allocations by submitting a crafted, yet small, XML document for parsing. This behavior can lead to denial of service (DoS) conditions due to resource exhaustion. The vulnerability is exploitable remotely (AV:N), requires no privileges (PR:N), and no user interaction (UI:N), making it relatively easy to exploit. The impact is limited to availability, with no direct confidentiality or integrity compromise. The CVSS v3.1 base score is 7.5, reflecting a high severity level. The exploitability is high (E:H), and the vulnerability has a confirmed fix (RL:T, RC:C), although no patch links are currently provided. No known exploits are reported in the wild yet. The root cause is the lack of input size validation or throttling mechanisms in libexpat's memory allocation routines during XML parsing, which can be abused to consume excessive system memory and potentially crash or destabilize applications relying on libexpat for XML processing.

For European organizations, this vulnerability poses a significant risk to any systems or applications that utilize libexpat for XML parsing. Given libexpat's widespread use in various open-source and commercial software stacks, including web servers, middleware, and embedded systems, the potential impact includes service outages, degraded performance, and operational disruptions due to memory exhaustion attacks. Critical infrastructure sectors such as finance, telecommunications, healthcare, and government services that rely on XML-based data interchange or configuration parsing could be particularly affected. The denial of service could be leveraged as part of a broader attack campaign to disrupt services or as a diversion for other malicious activities. Since exploitation requires no authentication or user interaction, attackers can remotely target vulnerable systems at scale. The absence of known exploits in the wild currently reduces immediate risk, but the ease of exploitation and high impact necessitate prompt mitigation to prevent future attacks.

European organizations should prioritize upgrading libexpat to version 2.7.2 or later, where this vulnerability is addressed. In environments where immediate upgrading is not feasible, implementing network-level protections such as input validation and limiting the size and complexity of XML documents accepted by applications can reduce exposure. Deploying Web Application Firewalls (WAFs) with rules to detect and block suspicious XML payloads may help mitigate exploitation attempts. Monitoring application logs for unusual memory usage or parsing errors can provide early warning signs of attempted exploitation. Additionally, organizations should conduct an inventory of software dependencies to identify all instances of libexpat usage, including indirect dependencies in third-party software. Applying runtime resource limits (e.g., memory quotas) on processes handling XML parsing can further contain the impact of potential attacks. Finally, maintaining up-to-date threat intelligence and patch management processes will ensure timely response to any emerging exploit developments.