CVE-2025-15537 is a heap-based buffer overflow vulnerability identified in the open-source mapping toolkit Mapnik, affecting versions 4.0 through 4.2.0. The flaw resides in the function mapnik::dbf_file::string_value within the source file plugins/input/shape/dbfile.cpp, which handles string extraction from DBF files used in shapefile formats. Improper handling of string data can lead to a heap overflow, corrupting memory and potentially allowing an attacker to execute arbitrary code or cause denial of service via application crashes. The vulnerability requires local access with low privileges (PR:L) and does not require user interaction (UI:N). The attack complexity is low (AC:L), but the scope is limited to the vulnerable process. The CVSS 4.0 vector indicates partial impacts on confidentiality, integrity, and availability, with no network attack vector, making remote exploitation infeasible. The vulnerability was responsibly disclosed but remains unpatched as of the publication date, and no known exploits are currently active in the wild. Mapnik is widely used in GIS applications for rendering maps and spatial data, often integrated into larger geospatial platforms. The vulnerability's exploitation could compromise systems that process untrusted shapefile data locally, especially in environments where multiple users have access to the same system or where untrusted data sources are processed without sufficient validation.

For European organizations, the impact of CVE-2025-15537 depends on their reliance on Mapnik for geospatial data processing. Organizations in sectors such as urban planning, transportation, environmental monitoring, and defense that utilize Mapnik could face risks of local privilege escalation or denial of service if attackers gain local access. The heap overflow could allow attackers to execute arbitrary code with the privileges of the Mapnik process, potentially leading to data corruption or system compromise. Since exploitation requires local access, insider threats or compromised user accounts pose the greatest risk. Disruption of GIS services could impact critical infrastructure operations and decision-making processes. Additionally, the lack of a patch increases exposure time, raising the risk of future exploitation. The medium severity rating reflects the limited attack vector but acknowledges the potential for significant impact if exploited in sensitive environments.

To mitigate CVE-2025-15537, European organizations should first restrict local access to systems running vulnerable Mapnik versions, enforcing strict user authentication and authorization policies. Implement application whitelisting and monitor for unusual process behavior or crashes related to Mapnik. Validate and sanitize all shapefile inputs before processing to reduce the risk of malicious data triggering the overflow. Employ endpoint detection and response (EDR) tools to detect exploitation attempts. Since no official patch is available yet, consider deploying temporary compensating controls such as running Mapnik processes with minimal privileges and isolating them in sandboxed environments or containers. Stay informed on vendor updates and apply patches promptly once released. Conduct internal audits to identify all instances of Mapnik and assess exposure. Finally, educate local users about the risks of executing untrusted data and enforce strict operational security policies.