Description
LMCache multiprocess mode, also called distributed mode, opens an unauthenticated ZeroMQ ROUTER so worker processes can register and share KV cache blocks. Messages on that socket are msgpack. 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. A single unauthenticated ZMQ DEALER message to the transport port (default 5555) therefore executes code as the user the LMCache process runs as. Official container images run that process as root. The transport binds to localhost unless the operator sets a routable address with --host, which is how multi-node deployments let peers connect. The decode path shipped in v0.3.9 and is present through v0.5.5, including the v0.5.6 release candidates. v0.5.6, published on 2026-10-14, removes pickle.loads from this path.
Published: 2026-10-07
Score: 9.8 Critical
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

Vendor Solution

Upgrade to LMCache 0.5.6 or later. That release replaces pickle in device IPC descriptors with versioned, typed MessagePack descriptors. Descriptors are validated before use, the wrapper type is chosen from a fixed local allowlist, and there is no pickle fallback. The change covers the ZeroMQ and gRPC paths. The wire format changed, so upgrade workers and servers together. The fix is PR #5644 and it is in the v0.5.6 tag. PR #5684, which binds the example Kubernetes deployment to localhost, and PR #5685, which runs the official images as a non-root user, were merged after the v0.5.6 tag was cut and are included in v0.5.7rc2. The v0.5.6 example deployment still passes --host 0.0.0.0, and the v0.5.6 images still run as root.

Tracking

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-w5f2-9q9c-ff4h LMCache: Remote code execution via unsafe deserialization in multiprocess mode transport
History

Thu, 29 Oct 2026 10:30:00 +0000

Type Values Removed Values Added
Description LMCache multiprocess mode, also called distributed mode, opens an unauthenticated ZeroMQ ROUTER so worker processes can register and share KV cache blocks. Messages on that socket are msgpack. 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. A single unauthenticated ZMQ DEALER message to the transport port (default 5555) therefore executes code as the user the LMCache process runs as. Official container images run that process as root. The transport binds to localhost unless the operator sets a routable address with --host, which is how multi-node deployments let peers connect. LMCache multiprocess mode, also called distributed mode, opens an unauthenticated ZeroMQ ROUTER so worker processes can register and share KV cache blocks. Messages on that socket are msgpack. 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. A single unauthenticated ZMQ DEALER message to the transport port (default 5555) therefore executes code as the user the LMCache process runs as. Official container images run that process as root. The transport binds to localhost unless the operator sets a routable address with --host, which is how multi-node deployments let peers connect. The decode path shipped in v0.3.9 and is present through v0.5.5, including the v0.5.6 release candidates. v0.5.6, published on 2026-10-14, removes pickle.loads from this path.
References

Wed, 07 Oct 2026 19:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Wed, 07 Oct 2026 11:45:00 +0000

Type Values Removed Values Added
First Time appeared Lmcache
Lmcache lmcache
Vendors & Products Lmcache
Lmcache lmcache

Wed, 07 Oct 2026 10:00:00 +0000

Type Values Removed Values Added
Description LMCache multiprocess mode, also called distributed mode, opens an unauthenticated ZeroMQ ROUTER so worker processes can register and share KV cache blocks. Messages on that socket are msgpack. 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. A single unauthenticated ZMQ DEALER message to the transport port (default 5555) therefore executes code as the user the LMCache process runs as. Official container images run that process as root. The transport binds to localhost unless the operator sets a routable address with --host, which is how multi-node deployments let peers connect.
Title LMCache Unauthenticated RCE in multiprocess mode via pickle deserialization
Weaknesses CWE-306
CWE-502
References
Metrics cvssV3_1

{'score': 9.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'}


cve-icon MITRE

Status: PUBLISHED

Assigner: JFROG

Published:

Updated: 2026-10-29T10:24:45.984Z

Reserved: 2026-10-04T11:50:41.213Z

Link: CVE-2026-105192

cve-icon Vulnrichment

Updated: 2026-10-07T17:48:33.165Z

cve-icon NVD

Status : Deferred

Published: 2026-10-07T10:17:32.647

Modified: 2026-10-29T11:17:24.523

Link: CVE-2026-105192

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-07T11:30:16Z

Weaknesses