External risk intelligence

Mooncake Transfer Engine Arbitrary Memory Read Write via TCP

CVE advisorySeverity: CRITICAL (CVSS 9.3)

CVE-2026-103764

The vulnerability exists in a transfer engine utilizing a TCP transport data port for communication. Because this component is designed to facilitate data transfer and synchronization across network nodes, it is commonly deployed as an externally reachable service or middleware endpoint, increasing the likelihood of exposure.

Halo Surface Signal: 4 out of 5 — likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A critical vulnerability exists in the Mooncake transfer engine that allows unauthenticated attackers to read and write arbitrary process memory. This could potentially expose sensitive data or lead to code execution. The main concern is confirming relevance and exposure to this technology.

Attackers can access memory via network.
High risk of data exposure or code execution.
Confirm if Mooncake transfer engine is in use.

Attack Path

How an attacker could exploit the issue

An attacker can target the Mooncake transfer engine through its TCP transport. By sending specially crafted data, they can trigger a vulnerability in how the engine reads session headers. This allows the attacker to read and write memory within the affected process, potentially leading to the disclosure of sensitive information or even arbitrary code execution.

No authentication needed to attack.
Crafted TCP data triggers vulnerability.
Sensitive data disclosure or code execution.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability could impact the confidentiality and integrity of process memory within the Mooncake transfer engine. When a specially crafted message is sent over the TCP transport data port, it may lead to the disclosure of sensitive information such as KV cache contents, prompts, and secrets, or the corruption of memory, potentially leading to unauthorized code execution.

Process memory and sensitive data.
Crafted network messages over TCP.
Unauthorized access and code execution.

Operational Fix

Recommended remediation, mitigation, and detection steps

This critical vulnerability in the Mooncake transfer engine likely impacts teams responsible for data transfer services, API gateways, or backend processing components. The first step should be to identify all instances of the affected technology, confirm their network exposure and business criticality, and then determine the accountable owner for remediation planning.

Confirm system ownership and business impact.
Verify network exposure and reachability.
Plan remediation based on confirmed risk.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

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Frequently asked questions

What is the Mooncake transfer engine?

Mooncake is a specialized transfer engine designed for high-performance data synchronization and movement. It is often used to manage key-value (KV) caches in AI or large-scale distributed computing environments, allowing systems to share data and prompts efficiently across network nodes.

What does CVE-2026-103764 mean?

This vulnerability is an untrusted pointer dereference, classified as CWE-822. In simple terms, the software fails to properly validate memory addresses provided in incoming network messages. An attacker can exploit this to trick the engine into reading from or writing to restricted memory locations instead of the intended data buffers.

How does an attacker trigger this vulnerability?

The flaw is triggered by sending a crafted SessionHeader over the TCP transport data port. The system does not require any authentication to process these requests. Note that simply having the service running is sufficient; valid user credentials or pre-existing sessions are not required to initiate the attack.

Is my system at risk according to Halo Surface Signal?

Halo Surface Signal identifies this as a 'Likely' risk because Mooncake is typically deployed as middleware or an externally reachable service to facilitate cross-node communication. If your instance is exposed to the internet or accessible via an untrusted network, the risk of unauthorized access to process memory is elevated.

What should I do if I use Mooncake?

Begin by auditing your infrastructure to locate all instances of the Mooncake transfer engine. Once identified, verify their network accessibility and determine if they are reachable from outside your trusted network. Finally, coordinate with your system owners to update to version 0.3.13 or later to resolve the underlying memory handling error.

References

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.