CVE-2026-15815: fallo de gravedad alta en Grafana OSS

Grafana OSS and Grafana Enterprise did not safely resolve symbolic links when extracting plugin archives. A crafted plugin archive can chain relative symbolic link entries to escape the plugin installation directory, writing arbitrary files and an executable backend binary outside that directory. The dropped executable runs with the privileges of the Grafana server process, resulting in remote code execution. Plugin archives are extracted before their signature is verified, so a valid plugin signature does not prevent the write. An operator can therefore be affected by installing a plugin that appears legitimate, as well as by installing a plugin from an arbitrary archive using grafana-cli, the GF_INSTALL_PLUGINS environment variable, or preinstall configuration. Grafana Enterprise is affected because it includes the same plugin extraction code as Grafana OSS.