Blinko versions up to 1.8.8 allow a directory traversal flaw when installing plugins. The installPlugin endpoint accepts an unsanitized plugin name, which can include "../" sequences that redirect file writes outside of the intended plugins directory. Because the official Docker image runs with root privileges, an authenticated attacker can overwrite a root‑owned startup file and thereby execute arbitrary code as the host user. The vulnerability is triggered via the plugin.installPlugin tRPC procedure, which is currently accessible to any authenticated user; self‑registration for an account is also possible, broadening the attack surface.

All installations of Blinko 1.8.8 and earlier are affected, including the default Docker image that runs as root. The flaw exists in the server/routerTrpc/plugin.ts file used by all supported environments and has no version restrictions beyond 1.8.8.

The CVSS score of 8.8 classifies the flaw as high severity. No EPSS score is available, and the vulnerability is not listed in the CISA KEV catalog, but the attack vector is inferred to be remote and requires authentication. An attacker can create an account or use existing credentials to trigger the traversal, overwrite critical startup files, and gain root‑level remote code execution on the host system. The risk is therefore high, especially for deployments using the unmodified official Docker image.