CVE-2026-65790 in Windows
Summary
by MITRE • 08/12/2026
Heap-based buffer overflow in Windows Message Queuing allows an authorized attacker to elevate privileges locally.
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Analysis
by VulDB Data Team • 08/12/2026
A heap-based buffer overflow vulnerability exists within the Windows Message Queuing (MSMQ) component that enables authenticated attackers to achieve local privilege escalation. This vulnerability stems from improper input validation and memory management practices within the messaging subsystem where insufficient bounds checking occurs during heap allocation operations. The flaw manifests when malicious input is processed through MSMQ's internal buffer handling mechanisms, causing data to be written beyond allocated memory boundaries in the heap space.
The technical implementation of this vulnerability involves a specific pattern where structured message data containing oversized payloads can trigger memory corruption within the heap management structures used by MSMQ. When an authenticated user submits carefully crafted message content that exceeds expected buffer sizes, the application fails to properly validate input lengths before copying data into allocated heap buffers. This results in overwriting adjacent memory locations including heap metadata, function pointers, or other critical control structures that govern program execution flow.
From an operational perspective this vulnerability presents a significant risk as it requires only local authentication to exploit, eliminating the need for network-based attack vectors or complex remote exploitation techniques. The privilege escalation occurs because MSMQ operates with elevated system privileges during message processing operations, allowing the attacker to leverage the heap overflow to manipulate memory contents in ways that can redirect execution flow or modify critical system structures. This creates a pathway for attackers to execute arbitrary code with SYSTEM level privileges, effectively compromising the entire Windows system.
The exploitability of this vulnerability aligns with common attack patterns documented in the attack mitigation framework where local privilege escalation techniques often target kernel-mode components or system services that operate with elevated permissions. The CWE classification for this vulnerability would fall under CWE-121 heap-based buffer overflow, which represents a well-established category of memory safety issues that have been the subject of numerous security advisories and exploit development practices. Organizations should implement immediate mitigations including applying Microsoft security patches, implementing application whitelisting controls, and monitoring for anomalous message queuing activities that might indicate exploitation attempts.
Security controls should focus on hardening the MSMQ service configuration by limiting unnecessary permissions and implementing strict input validation policies for all message content. Network segmentation and privilege separation principles should be enforced to minimize the impact of potential exploitation. The ATT&CK framework categorizes this type of vulnerability under privilege escalation techniques, specifically targeting system services and kernel components that provide elevated access capabilities. Regular security assessments should include verification of MSMQ configurations and monitoring for unauthorized access attempts or unusual system behavior patterns that may indicate successful exploitation of this heap-based buffer overflow vulnerability.
Organizations must prioritize patch management processes to ensure timely deployment of Microsoft security updates addressing this specific vulnerability while maintaining continuous monitoring of system logs for indicators of compromise. The remediation approach should include comprehensive security configuration reviews of all Windows Message Queuing implementations across the enterprise environment to prevent unauthorized access and exploitation opportunities that could lead to full system compromise through local privilege escalation attacks.