CVE-2025-63658 is a stack overflow vulnerability located in the mk_http_index_lookup function within the mk_server/mk_http.c source file of the Monkey HTTP server. This flaw arises when the server processes a crafted HTTP request that triggers a buffer overflow on the stack, leading to memory corruption. The consequence of this overflow is a Denial of Service (DoS) condition, where the server crashes or becomes unresponsive, disrupting normal operations. The vulnerability does not require any form of authentication, meaning any remote attacker with network access to the server can exploit it. Although no specific affected versions are listed, the vulnerability is tied to the commit f37e984, indicating it affects versions containing this code base. No public exploits have been reported yet, and no official patch or CVSS score is available at this time. The vulnerability primarily impacts the availability of services hosted on the Monkey HTTP server, which is a lightweight web server used in embedded systems and some specialized environments. The lack of a CVSS score necessitates an assessment based on the nature of the vulnerability, its exploitability, and potential impact.

The primary impact of CVE-2025-63658 is on the availability of services running on the Monkey HTTP server. Successful exploitation leads to a server crash, causing downtime and potential disruption of business-critical applications or services. For European organizations, especially those in sectors relying on embedded systems or lightweight HTTP servers for IoT, telecommunications, or specialized web services, this could mean service interruptions and operational delays. Although the vulnerability does not directly compromise confidentiality or integrity, the resulting DoS could indirectly affect business continuity and service level agreements. Additionally, repeated exploitation attempts could lead to resource exhaustion or increased operational costs due to recovery efforts. The absence of known exploits currently reduces immediate risk but does not eliminate the threat, especially as attackers may develop exploits once the vulnerability becomes widely known.

1. Monitor official Monkey HTTP server repositories and security advisories for patches addressing this vulnerability and apply them promptly once available. 2. Restrict network access to the Monkey HTTP server to trusted IP addresses or internal networks using firewalls or access control lists to reduce exposure. 3. Implement Web Application Firewalls (WAFs) or intrusion detection systems capable of detecting and blocking malformed or suspicious HTTP requests targeting the mk_http_index_lookup function. 4. Conduct regular security assessments and penetration tests focusing on HTTP services to identify potential exploitation attempts. 5. Employ rate limiting and connection throttling to mitigate the impact of potential DoS attacks. 6. Maintain robust logging and monitoring to detect unusual server crashes or HTTP request patterns indicative of exploitation attempts. 7. Consider deploying redundancy and failover mechanisms to minimize service disruption in case of a successful attack.