Tileserver - XSS (CVE-2025-44136)

CVE-2025-44136 is a critical cross-site scripting (XSS) vulnerability in MapTiler Tileserver-php v2.0, where the "layer" GET parameter is improperly handled and reflected in error messages without proper HTML encoding. This flaw allows unauthenticated attackers to inject and execute arbitrary HTML or JavaScript code in a victim's browser, potentially leading to session hijacking, credential theft, or other malicious actions.

CrowdSec has been tracking this vulnerability and its exploits since 26th of November 2025.

CrowdSec network observations suggest that most exploitation of CVE-2025-44136 involves focused reconnaissance to identify viable targets. Attackers typically tailor their campaigns based on system exposure and configuration. It is unlikely that a given attack is accidental. Telemetry from the CrowdSec network also shows that exploitation activity for CVE-2025-44136 remains steady week-over-week. Attack volumes are consistent with long-term trends, indicating sustained interest from threat actors. CVE-2025-44136 continues to be an active part of the threat landscape and will likely remain this way for the forseeable future.

Attackers exploit this vulnerability by sending requests to URLs like /tileserver.php/wmts/x/1/1/asd with a crafted layer parameter containing malicious JavaScript, resulting in reflected XSS in error messages.