# CVE-2026-103760: Mooncake transfer engine denial of service in handshake RPC

Source: https://junglewise.ai/threats/cve-2026-103760-mooncake-transfer-engine-through-0-3-13-post1-contains-a-denial  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-01. Updated: 2026-10-05  
License: CC BY 4.0 with a link back

CVE-2026-103760 · Severity: medium · CVSS 5.9 · Published 2026-10-01

Mooncake is a serving platform for large language models that manages data transfer and metadata operations. An unauthenticated remote attacker can send malformed requests to the handshake RPC port, blocking the daemon's listener thread and preventing all subsequent handshakes, metadata fetches, and probe operations. This causes a complete service outage for any systems relying on Mooncake's transfer capabilities.

Vendors: [Kvcache-Ai](https://junglewise.ai/threats/vendors/kvcache-ai).

## Quick answers

**Is CVE-2026-103760 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-103760 being exploited in the wild.

**How severe is CVE-2026-103760?** Medium severity, with a CVSS score of 5.9, published 1 October 2026.

**Which products and versions are affected?** Kvcache-Ai Mooncake transfer engine through 0.3.13.post1.

**Is there a fix for CVE-2026-103760?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-103760 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-103760?** Check whether you run Kvcache-Ai Mooncake transfer engine at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability exists in SocketHandShakePlugin's listener thread, which can be stalled in writeFully() when handling a Metadata request if the attacker never reads the reply. The single-threaded design means one blocked write operation blocks all subsequent handshakes, metadata fetches, notify, and probe requests. This is a resource exhaustion denial of service requiring only network access to the RPC port and no authentication.

## Affected products

- KVCache AI Mooncake transfer engine through 0.3.13.post1

## Timeline

- 2026-10-01: disclosed

## References

- [https://github.com/kvcache-ai/Mooncake](https://github.com/kvcache-ai/Mooncake)
- [https://github.com/kvcache-ai/Mooncake/blob/719735896c86b56fabec6cf3e825fb2ea640597a/mooncake-transfer-engine/src/transfer_metadata_plugin.cpp](https://github.com/kvcache-ai/Mooncake/blob/719735896c86b56fabec6cf3e825fb2ea640597a/mooncake-transfer-engine/src/transfer_metadata_plugin.cpp)

## Related threats

- [Mooncake transfer engine untrusted pointer dereference](https://junglewise.ai/threats/cve-2026-103764-mooncake-transfer-engine-before-0-3-13-contains-an-untrusted)