CVE-2025-52186 is a Server-Side Request Forgery (SSRF) vulnerability identified in the Lichess lila platform before commit 11b4c0fb00f0ffd823246f839627005459c8f05c, published on November 13, 2025. The vulnerability exists in the game export API, specifically in the handling of the 'players' parameter. This parameter is passed directly to an internal HTTP client without any validation or sanitization, enabling remote attackers to craft requests that cause the server to initiate HTTP requests to arbitrary URLs. SSRF vulnerabilities allow attackers to bypass firewall restrictions and access internal resources that are not directly accessible from the internet. Potential exploitation scenarios include scanning internal networks, accessing metadata services in cloud environments, or interacting with internal APIs, which can lead to information disclosure or further compromise. The vulnerability does not require authentication or user interaction, increasing its risk profile. Although no public exploits have been reported, the lack of input validation and the direct use of user-supplied data in HTTP requests make this vulnerability straightforward to exploit. The affected software is Lichess lila, an open-source chess platform widely used for online chess play and analysis. The absence of a CVSS score necessitates a severity assessment based on impact and exploitability factors.

For European organizations, the impact of CVE-2025-52186 can be significant, especially for those hosting their own Lichess lila instances or integrating the platform into their services. Exploitation could allow attackers to perform internal network reconnaissance, potentially exposing sensitive internal services or data repositories. This could lead to unauthorized access to confidential information, disruption of internal services, or serve as a pivot point for further attacks within the organization's network. Organizations using cloud infrastructure may be particularly vulnerable if the SSRF can be leveraged to access cloud metadata services, leading to credential theft or privilege escalation. The vulnerability's ability to be exploited without authentication increases the risk of automated attacks and broad scanning. Given the popularity of Lichess in Europe and the potential for internal network exposure, this vulnerability could affect educational institutions, chess federations, and private companies using the platform. The absence of known exploits currently limits immediate widespread impact, but the risk remains high due to the nature of SSRF vulnerabilities.

To mitigate CVE-2025-52186, organizations should immediately update Lichess lila to the fixed version that includes the commit 11b4c0fb00f0ffd823246f839627005459c8f05c or later. If updating is not immediately possible, implement strict input validation and sanitization on the 'players' parameter to ensure only expected and safe URLs or identifiers are accepted. Employ network-level controls to restrict outbound HTTP requests from the Lichess server to only trusted destinations, minimizing the risk of SSRF exploitation. Use web application firewalls (WAFs) with rules designed to detect and block SSRF attack patterns. Monitor server logs for unusual outbound HTTP requests or patterns indicative of SSRF attempts. Additionally, conduct internal network segmentation to limit the exposure of sensitive services to the Lichess server. Regularly audit and review the platform's API endpoints for similar vulnerabilities and apply secure coding practices to prevent injection of untrusted data into internal requests.