CVE-2026-69096: OpenWrt luci-app-dockerman Read ACL Remote Code Execution

OpenWrt luci-app-dockerman (LuCI master and openwrt-25.12 snapshots containing the ucode dockerrpc.uc RPC backend after the JS/ucode conversion) contains an OS command injection vulnerability. The package's read ACL grants broad ubus access to docker. / docker.container., which exposes the docker.container.ttydstart method even though it performs mutating operations. The runttyd handler builds a shell command from the request-controlled id, cmd, and uid fields and passes it to system() without quoting or argv-style execution in the rpcd root context. An authenticated attacker holding only the luci-app-dockerman read ACL can inject shell metacharacters (e.g., in id) to execute arbitrary commands as root via an HTTP POST to /ubus. openwrt-24.10 and openwrt-23.05 do not contain this backend and are not affected; no patched version was known as of the advisory.