CVE-2025-63657 is an out-of-bounds read vulnerability located in the mk_mimetype_find function within the mk_server/mk_mimetype.c source file of the Monkey HTTP server. The vulnerability arises when the server processes certain crafted HTTP requests that cause it to read memory outside the intended bounds. This memory access violation can lead to a crash or instability of the server process, resulting in a Denial of Service (DoS) condition. The vulnerability does not require authentication, meaning any remote attacker capable of sending HTTP requests to the server can exploit it. The affected versions are not explicitly specified, and no patches or fixes have been published at the time of disclosure. There are no known exploits in the wild, indicating limited or no active exploitation currently. The lack of a CVSS score necessitates an independent severity assessment. The vulnerability impacts the availability of the Monkey HTTP server, potentially disrupting web services or applications relying on it. Given the nature of the flaw, exploitation is straightforward for attackers with network access to the server, and no user interaction is required. The vulnerability is a classic example of improper bounds checking leading to memory safety issues, which remain a common source of security problems in server software.

For European organizations, the primary impact of CVE-2025-63657 is the potential disruption of web services hosted on Monkey HTTP servers. This could affect internal applications, public-facing websites, or APIs, leading to downtime and loss of availability. Organizations relying on Monkey server for critical infrastructure may experience service outages, impacting business continuity and user trust. Although no data breach or integrity compromise is indicated, the DoS condition could be leveraged as part of a broader attack strategy to degrade service or distract from other malicious activities. The lack of known exploits reduces immediate risk, but the vulnerability's presence in network-facing infrastructure means it could be targeted by opportunistic attackers or incorporated into automated scanning tools. European entities with regulatory obligations around service availability and incident response may face compliance challenges if disruptions occur. The impact is heightened in sectors where uptime is critical, such as finance, healthcare, and government services.

1. Immediately restrict network access to Monkey HTTP servers to trusted IP addresses and internal networks to reduce exposure. 2. Implement Web Application Firewalls (WAFs) or intrusion prevention systems capable of detecting and blocking malformed HTTP requests that could trigger the vulnerability. 3. Monitor server logs for unusual or malformed HTTP requests targeting the mk_mimetype_find function or related endpoints. 4. Establish robust incident response procedures to quickly identify and mitigate DoS conditions. 5. Engage with Monkey server maintainers or community to track the release of official patches or updates addressing this vulnerability and apply them promptly. 6. Consider deploying alternative HTTP server software with a strong security track record if Monkey server usage is not critical. 7. Conduct regular security assessments and penetration testing focused on HTTP server components to identify similar vulnerabilities proactively. 8. Educate network and security teams about this vulnerability to enhance detection and response capabilities.