CVE-2025-63652 is a use-after-free vulnerability identified in the mk_http_request_end function within the Monkey HTTP server's source code (mk_server/mk_http.c) at commit f37e984. A use-after-free occurs when a program continues to use memory after it has been freed, leading to undefined behavior, crashes, or potential code execution. In this case, the vulnerability allows an attacker to send a crafted HTTP request that triggers the use-after-free condition, causing the server process to crash and resulting in a Denial of Service (DoS). The vulnerability does not require authentication or user interaction, making it relatively easy to exploit remotely. The affected versions are not explicitly specified, indicating the need for organizations to verify their deployed Monkey server versions against the vulnerable commit. No patches or fixes are currently linked, and no known exploits have been reported in the wild as of the publication date. The lack of a CVSS score necessitates an independent severity assessment. The vulnerability impacts availability by crashing the server, potentially disrupting web services relying on Monkey HTTP server. Since Monkey is a lightweight HTTP server often used in embedded systems or specialized environments, the scope of impact depends on its deployment scale within an organization. The vulnerability's exploitation vector is straightforward, involving sending a malicious HTTP request, which could be automated by attackers scanning for vulnerable servers. This makes timely mitigation critical to prevent service outages.

For European organizations, the primary impact of CVE-2025-63652 is the potential disruption of web services hosted on Monkey HTTP servers due to Denial of Service attacks. This can affect business continuity, especially for organizations relying on Monkey in production environments or embedded systems. Service outages can lead to loss of customer trust, operational delays, and financial losses. Additionally, if Monkey servers are part of critical infrastructure or industrial control systems, the DoS could have broader operational consequences. Since the vulnerability does not allow direct code execution or data compromise, confidentiality and integrity impacts are minimal. However, the availability impact is significant, particularly for organizations with high uptime requirements. The ease of exploitation without authentication increases the risk of opportunistic attacks. European entities with limited resources for rapid patching or monitoring may face prolonged exposure. The lack of known exploits currently provides a window for proactive mitigation. Overall, the threat could disrupt services but does not appear to enable data breaches or persistent compromise.

1. Verify the version of Monkey HTTP server in use and identify if it includes the vulnerable commit f37e984 or related code. 2. Monitor official Monkey project channels and security advisories for patches or updates addressing CVE-2025-63652 and apply them promptly once available. 3. Implement network-level filtering to block or rate-limit suspicious or malformed HTTP requests that could trigger the vulnerability, using web application firewalls (WAFs) or intrusion prevention systems (IPS). 4. Enable detailed logging and monitoring of HTTP request patterns to detect anomalous traffic indicative of exploitation attempts. 5. Employ redundancy and failover mechanisms for critical services running on Monkey to minimize downtime in case of DoS. 6. Conduct internal security assessments and penetration testing to simulate exploitation and validate defenses. 7. Restrict exposure of Monkey HTTP servers to untrusted networks where possible, using VPNs or access control lists. 8. Educate system administrators about the vulnerability and encourage rapid incident response procedures. 9. Consider alternative HTTP servers with active security support if Monkey is not essential or lacks timely patches. 10. Maintain up-to-date backups and recovery plans to restore services quickly after an incident.