CVE-2025-11539: fallo crítico en grafana-image-renderer

Grafana Image Renderer is vulnerable to remote code execution due to an arbitrary file write vulnerability. This is due to the fact that the /render/csv endpoint lacked validation of the filePath parameter that allowed an attacker to save a shared object to an arbitrary location that is then loaded by the Chromium process. Instances are vulnerable if: 1. The default token ("authToken") is not changed, or is known to the attacker. 2. The attacker can reach the image renderer endpoint. This issue affects grafana-image-renderer: from 1.0.0 through 4.0.16.