CVE-2026-107204

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 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 mode opens an unauthenticated ZeroMQ ROUTER for worker registration and KV cache sharing. Messages are msgpack, and extension code 1 is passed to DeviceIPCWrapper.Deserialize, which calls pickle.loads before the handler runs. A single unauthenticated ZMQ DEALER message to the transport port (default 5555) executes code as the LMCache user. Official containers run as root. The transport binds to localhost unless --host is set for multi-node deployments.

Vulnerability in LMCache up to 0.4.6. The hex_hash_to_int16 function in lmcache/integration/vllm/utils.py (KV Cache Handler component) uses a weak hash. Attack requires local access and high complexity. Exploit is publicly available.