CVE-2026-85334 in Windows
Summary
by MITRE • 10/14/2026
Out-of-bounds read in Windows Message Queuing Queue Manager allows an unauthorized attacker to disclose information over a network.
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Analysis
by VulDB Data Team • 10/14/2026
The vulnerability identified as an out-of-bounds read within the Microsoft Windows Message Queuing (MSMQ) Queue Manager represents a critical security flaw that enables remote attackers to extract sensitive system information without prior authentication. This specific defect resides in the core component responsible for managing message queues, which is integral to inter-process communication and distributed application architectures on Windows systems. The vulnerability arises when the Queue Manager processes specially crafted network packets or malformed queue requests, leading it to access memory locations beyond the intended buffer boundaries. Because this operation constitutes a read rather than a write, it does not typically result in immediate code execution but instead allows the attacker to leak contents of adjacent memory regions into the response stream sent back over the network.
From a technical perspective, this flaw is classified under CWE-125, which defines out-of-bounds read vulnerabilities where software reads data past the end or before the beginning of the intended buffer. In the context of MSMQ, the Queue Manager handles various message formats and routing instructions that require parsing complex structures. If input validation fails to properly check array indices or string lengths during this parsing phase, the application may retrieve uninitialized memory or sensitive kernel-mode data. This behavior aligns with ATT&CK technique T1005, which covers Data from Local System, specifically through mechanisms like file and directory discovery or direct memory access via network protocols. The attacker leverages the network-facing nature of MSMQ to trigger this condition remotely, making it a significant risk for internet-exposed servers running message queuing services.
The operational impact of this vulnerability is primarily centered on information disclosure rather than system compromise through privilege escalation or denial of service in its initial form. However, leaked memory contents can include cryptographic keys, session tokens, internal IP addresses, or other confidential data that facilitates further attacks such as credential theft or lateral movement within a network environment. An unauthorized attacker who exploits this flaw can gather intelligence about the target infrastructure with minimal interaction required beyond sending specific crafted packets to port 1801 or related MSMQ endpoints. This passive reconnaissance capability significantly lowers the barrier for subsequent exploitation attempts, potentially leading to more severe consequences if combined with other vulnerabilities in the same system stack.
Mitigation strategies must focus on both immediate remediation and long-term architectural adjustments. The most effective defense is applying the latest security updates provided by Microsoft that patch this specific out-of-bounds read condition within the Queue Manager component. Organizations should ensure that all Windows systems running MSMQ are fully patched to address known CVEs associated with message queuing services. Additionally, since MSMQ has been deprecated in modern Windows versions and replaced by more secure messaging frameworks like Azure Service Bus or RabbitMQ for new deployments, it is highly recommended to disable the MSMQ service if it is not strictly required for legacy applications. Network segmentation should also be implemented to restrict access to ports used by MSMQ from untrusted networks, thereby reducing the attack surface available to remote adversaries attempting to exploit this information disclosure flaw.