CVE-2025-59375 is a vulnerability identified in the libexpat XML parsing library, specifically in versions prior to 2.7.2. The root cause is an allocation of resources without proper limits or throttling (CWE-770), which allows an attacker to craft a small XML document that triggers disproportionately large dynamic memory allocations during parsing. This can exhaust system memory resources, leading to denial-of-service (DoS) conditions by crashing the application or severely degrading its performance. The vulnerability is remotely exploitable without requiring any authentication or user interaction, as the attacker only needs to submit a malicious XML document to a service or application that uses the vulnerable libexpat version. The CVSS v3.1 base score is 7.5, reflecting high impact on availability and ease of exploitation. Although no known exploits have been reported in the wild, the vulnerability poses a significant risk to any software or service relying on libexpat for XML processing, especially those exposed to untrusted inputs. The lack of patch links suggests that the fix is included in libexpat 2.7.2 or later, emphasizing the importance of timely updates. This vulnerability highlights the critical need for resource management controls in XML parsers to prevent resource exhaustion attacks.

For European organizations, the primary impact of CVE-2025-59375 is the potential for denial-of-service attacks that can disrupt critical services relying on XML data processing. This includes web services, middleware, and enterprise applications that embed libexpat for XML parsing. Disruptions can lead to service outages, loss of availability, and operational downtime, which may affect customer trust and regulatory compliance, especially under GDPR where service continuity is important. Organizations in sectors such as finance, telecommunications, government, and healthcare, which often process large volumes of XML data, are particularly vulnerable. The vulnerability could be exploited to target critical infrastructure or cloud services hosted in Europe, amplifying the risk. Additionally, the absence of confidentiality or integrity impact means data breaches are unlikely, but the availability impact alone can have severe business consequences. The ease of exploitation and remote attack vector increase the threat level, making proactive mitigation essential.

1. Upgrade libexpat to version 2.7.2 or later immediately to ensure the vulnerability is patched. 2. Implement strict input validation and size limits on XML documents before parsing to prevent maliciously crafted payloads from triggering excessive memory allocation. 3. Employ resource monitoring and throttling mechanisms in applications that use libexpat to detect and limit abnormal memory usage during XML processing. 4. Use sandboxing or containerization to isolate XML parsing processes, minimizing the impact of potential DoS attacks. 5. Review and update incident response plans to include scenarios involving resource exhaustion attacks. 6. For organizations developing software that includes libexpat, consider integrating fuzz testing and resource usage analysis in the development lifecycle to detect similar issues proactively. 7. Monitor security advisories and threat intelligence feeds for any emerging exploits related to this vulnerability.