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Vulnerability Deep Dive
CVE-2026-65790 is a heap-based buffer overflow vulnerability identified in the Microsoft Windows Message Queuing (MSMQ) service. The flaw stems from a boundary error within the MSMQ Queue Manager, where the service improperly handles bounds checking when processing input data. An authorized local attacker can exploit this vulnerability by sending specially crafted data to the vulnerable service. This triggers the heap-based buffer overflow, corrupting memory and potentially allowing the attacker to execute arbitrary code.
Because the MSMQ service typically runs with high system privileges, successful exploitation enables an attacker to elevate their privileges locally. This could lead to a complete compromise of the affected system, as the attacker could gain SYSTEM-level access and perform actions such as installing programs, viewing, changing, or deleting data, or creating new accounts with full user rights. The vulnerability is classified under CWE-122 and has been assigned a CVSS v3.1 base score of 7.8 (HIGH), reflecting its potential for significant impact on confidentiality, integrity, and availability.
DailyCVE Form:
Platform: Windows 10, 11, Server
Version: 1607–22H2, 23H2–26H1, 2012–2025
Vulnerability: Heap Buffer Overflow
Severity: 7.8 HIGH
date: August 11, 2026
Prediction: Expected Patch Date: August 2026
What Undercode Say:
Analytics from threat intelligence platforms indicate that the vulnerability is local in nature, requiring authenticated access. The EPSS score is reported to be less than 1%, suggesting a low probability of widespread exploitation in the wild. It has not been listed in the CISA KEV (Known Exploited Vulnerabilities) catalog, which further indicates that active exploitation is not currently prevalent.
Check if MSMQ service is installed and running
Get-WindowsFeature -Name MSMQ | Where-Object Installed -EQ $true
Get-Service -Name MSMQ | Select-Object Name, Status, StartType
Check for the specific patch related to CVE-2026-65790
Get-HotFix | Where-Object {$_.HotFixID -like "65790"}
Exploit: (Educational Purposes!)
The exploitation process involves a local, authorized attacker crafting a malicious payload to trigger the overflow in the MSMQ Queue Manager.
This is a conceptual example for educational purposes only.
It does not represent a working exploit for CVE-2026-65790.
import struct
import subprocess
Hypothetical payload to trigger a heap overflow
payload = b"A" 1024 Overflow data
payload += struct.pack("<I", 0x41414141) Overwrite return address
Hypothetical function to send the payload to MSMQ
subprocess.run(["msmq_send.exe", payload])
print("Payload sent to vulnerable service (hypothetical).")
Protection:
Apply Updates: The primary mitigation is to install the security update provided by Microsoft, which is typically released on Patch Tuesday.
Disable Unnecessary Services: If the MSMQ service is not required, it should be disabled to eliminate the attack surface.
Least Privilege: Ensure that only trusted users have permissions to interact with the Message Queuing service.
Impact:
Privilege Escalation: An attacker can elevate their privileges to SYSTEM level, gaining complete control over the affected system.
System Compromise: Full compromise of the vulnerable system, allowing for data theft, malware installation, and further network attacks.
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Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
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