CVE-2026-107204

LMCache through 0.5.5 contains a missing authentication vulnerability in the multiprocess mode HTTP server that allows remote unauthenticated attackers to access management endpoints listening on all interfaces by default. Attackers can read environment credentials via GET /env and configuration via GET /config, clear caches, delete cache objects, and modify tenant quotas to evict other tenants' cached data.

LMCache multiprocess (distributed) mode opens an unauthenticated ZeroMQ ROUTER socket where workers register and share KV cache blocks. Extension code 1 is passed to DeviceIPCWrapper.Deserialize, which calls pickle.loads while the server is still decoding request arguments and before the handler runs, so a single unauthenticated ZMQ DEALER message to the transport port (default 5555) executes code as the LMCache process user.

LMCache through 0.5.5 contains a server-side request forgery vulnerability in its frontend monitoring service that allows unauthenticated attackers to bypass the proxy allowlist by registering arbitrary hosts. Attackers can add entries via POST /api/proxies and then use /proxy or /proxy2 to reach internal hosts, read responses, and tamper with nodes or stop the heartbeat.

LMCache through 0.5.5 contains a missing authentication vulnerability in the multiprocess coordinator that allows remote unauthenticated attackers to access its HTTP fleet control API listening on all interfaces by default. Attackers can register or deregister instances via /instances, overwrite quotas via /quota endpoints, inject events via /events, and enumerate /directory/keys to disrupt caching and disclose placement metadata.

LMCache up to 0.5.4 contains a vulnerability in the hex_hash_to_int16 function in lmcache/integration/vllm/utils.py, involving the use of a weak hash. The attack requires local access and high complexity, and the exploit has been published. A fix is available in version 0.5.5.