CVE-2026-103764 in Mooncake
Summary
by MITRE • 10/02/2026
Mooncake transfer engine before 0.3.13 contains an untrusted pointer dereference in ServerSession::readHeader that allows unauthenticated attackers to read and write arbitrary process memory via the TCP transport data port. Attackers can send a crafted SessionHeader with arbitrary addr and size values using READ or WRITE opcodes to disclose KV cache contents, prompts and secrets or corrupt memory toward code execution.
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Analysis
by VulDB Data Team • 10/02/2026
The Mooncake transfer engine prior to version 0.3.13 suffers from a critical untrusted pointer dereference vulnerability located within the ServerSession::readHeader function. This flaw stems from insufficient validation of input parameters received over network interfaces, specifically when processing session headers transmitted via TCP transport data ports. The architecture allows for direct interaction with memory management operations without adequate authentication or integrity checks on the metadata provided by the client. Consequently, any unauthenticated actor capable of establishing a connection to this port can exploit this lack of verification to manipulate how the server handles read and write requests against its own process space.
The technical mechanism of exploitation involves crafting malicious SessionHeader structures that contain arbitrary values for memory addresses and sizes. By utilizing READ or WRITE opcodes within these headers, an attacker instructs the vulnerable function to dereference pointers supplied by the client rather than validating them against expected bounds or authorized regions. This effectively grants the remote adversary direct read-write access to arbitrary process memory. The absence of boundary checks means that out-of-bounds accesses are not prevented, allowing the application to interact with memory segments it should never touch, including kernel space if privilege escalation occurs through other vectors, though primarily targeting user-space application memory in this context.
The operational impact of this vulnerability is severe due to its potential for both information disclosure and remote code execution. Attackers can leverage the READ opcode to exfiltrate sensitive data stored within the Mooncake process memory, such as key-value cache contents, prompt inputs which may contain proprietary or personal information, and cryptographic secrets like API keys or authentication tokens. Furthermore, by using the WRITE opcode, an attacker can corrupt critical memory structures, overwrite function pointers, or manipulate control flow elements to achieve arbitrary code execution on the affected system. This transforms a simple data exposure risk into a full compromise of the host environment, potentially leading to lateral movement within internal networks if Mooncake is deployed in a cluster configuration.
This vulnerability aligns with Common Weakness Enumeration (CWE) identifiers such as CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer and CWE-284 Improper Access Control. In terms of the MITRE ATT&CK framework, this exploit maps to techniques involving Tactic 1071 Application Layer Protocol for Command and Control or Data Exfiltration over C2 Channel, specifically leveraging valid network protocols to bypass perimeter defenses. The lack of authentication also relates to CWE-345 Insufficient Verification of Data Authenticity.
To mitigate this risk, organizations must immediately upgrade the Mooncake transfer engine to version 0.3.13 or later where these validation checks have been implemented. Until an update is applied, network segmentation strategies should be employed to restrict access to the TCP transport data port exclusively to trusted internal services that require legitimate interaction with the transfer engine. Additionally, implementing strict firewall rules and intrusion detection system signatures targeting malformed SessionHeader structures can provide a layer of defense against exploitation attempts by unauthenticated actors scanning for this specific vulnerability pattern.