CVE-2025-51495 identifies an integer overflow vulnerability within the WebSocket component of the Mongoose networking library, specifically affecting versions 7.5 through 7.17. The vulnerability arises when the component processes WebSocket requests containing specially crafted payloads that cause an integer overflow during internal calculations. This overflow can lead to an application crash, resulting in denial of service (DoS). Furthermore, if downstream vendors integrate Mongoose improperly, the integer overflow may be exploited to trigger a buffer overflow, which could allow an attacker to execute arbitrary code or cause more severe memory corruption. The vulnerability requires no privileges or user interaction and can be exploited remotely over the network. The CVSS 3.1 base score of 7.5 reflects the high impact on availability due to the DoS potential, with no impact on confidentiality or integrity directly reported. Although no public exploits are currently known, the vulnerability poses a significant risk to applications relying on Mongoose’s WebSocket functionality, especially in embedded or IoT devices where Mongoose is commonly used. The underlying weakness corresponds to CWE-190 (Integer Overflow or Wraparound), a common issue in software that handles untrusted input without proper bounds checking or validation.

For European organizations, the primary impact is the risk of denial of service through application crashes caused by malicious WebSocket requests. This can disrupt critical services, especially in sectors relying on real-time communication or embedded systems such as industrial control, telecommunications, or IoT deployments. In cases where downstream vendors have integrated Mongoose improperly, the risk escalates to potential remote code execution via buffer overflow, which could compromise system integrity and lead to data breaches or persistent system compromise. The disruption could affect service availability, damage organizational reputation, and incur regulatory penalties under frameworks like GDPR if service interruptions impact personal data processing. The threat is particularly relevant for companies developing or deploying web servers, embedded devices, or networked applications using Mongoose, which is popular in Europe’s growing IoT and embedded markets.

European organizations should immediately identify all systems and applications using Mongoose versions 7.5 through 7.17, especially those exposing WebSocket interfaces. They should apply patches or updates from the Mongoose project as soon as they become available. If patches are not yet released, organizations should implement network-level protections such as Web Application Firewalls (WAFs) configured to detect and block malformed WebSocket requests. Vendors integrating Mongoose should review their code to ensure proper input validation and bounds checking to prevent integer overflow and buffer overflow conditions. Employing runtime protections like Address Space Layout Randomization (ASLR) and Data Execution Prevention (DEP) can mitigate exploitation impact. Additionally, monitoring for unusual WebSocket traffic patterns and implementing rate limiting can reduce the risk of exploitation attempts. Finally, organizations should engage with their supply chain to verify that third-party products using Mongoose have addressed this vulnerability.