The vulnerability resides in Gitea's act_runner component when using the Docker backend starting at act 0.262.0. It passes workflow-defined container.options directly to Docker's HostConfig, preserving options such as --pid=host, --cap-add, and --security-opt even when privileged mode is disabled. A user capable of initiating a workflow can therefore spawn a container with host namespaces and unrestricted capabilities, allowing escape to the host system with root privileges.

Affected systems include installations of Gitea act_runner using Docker as the execution platform, specifically version act 0.262.0 and subsequent releases that have not yet applied a patch. No other vendors or products are listed.

The CVSS score of 9.4 indicates severe risk, and although the EPSS score is unavailable, the lack of a KEV listing does not diminish its potential for exploitation. An attacker only needs permissions to trigger a workflow on a Docker-backed runner, after which the vulnerability can be exploited to obtain root access on the host. The attack is local from the perspective of the runner user but results in full host compromise.