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CVE-2026-58651 is a high-severity vulnerability identified in Microsoft Office Word. The core of the issue is a heap-based buffer overflow, a type of memory corruption vulnerability classified under CWE-122. This flaw exists in how Microsoft Word handles specific data when parsing a maliciously crafted file.
An unauthorized attacker can exploit this vulnerability to execute arbitrary code locally on a victim’s machine. The attack vector is local and requires user interaction, meaning an attacker must convince a user to open a specially crafted Word document, typically delivered via email or other means. Upon opening the file, the heap-based buffer overflow is triggered, allowing the attacker to gain control of the affected system.
The exploitation of this vulnerability compromises the confidentiality, integrity, and availability of the system, as the attacker can execute code with the same privileges as the user who opened the malicious document. The vulnerability affects a wide range of Microsoft Office products, including Microsoft 365 Apps for Enterprise, Office LTSC 2021, Office LTSC 2024, and their respective macOS versions. With a CVSS base score of 7.8, it is classified as a High severity vulnerability. As of the latest information, no official vendor fix or patch has been released, leaving all current versions of these products potentially vulnerable.
DailyCVE Form:
Platform: ……. Microsoft Office
Version: …….. 365, 2021, 2024
Vulnerability :…… Heap Buffer Overflow
Severity: ……. 7.8 HIGH
date: ………. 2026-08-11
Prediction: ….. 2026-09-08
What Undercode Say:
Analytics show active scanning for Word document parsing vulnerabilities. Below are bash commands for simulation and detection:
Simulate a heap overflow attempt (Educational Purposes Only) echo "Simulating heap overflow on Word document parser..." This is a placeholder for a proof-of-concept trigger Example: python3 trigger_cve-2026-58651.py --file malicious.doc Check for vulnerable Office versions via registry (Windows) reg query "HKLM\Software\Microsoft\Office\ClickToRun\Configuration" /v VersionToReport Monitor for suspicious Word processes spawning unusual child processes watch -n 1 'ps aux | grep -i "WINWORD.EXE"'
Exploit: (Educational Purposes!)
The exploit relies on crafting a Word document with a specific structure that, when parsed, writes data beyond the allocated heap buffer. This corrupts adjacent memory, potentially overwriting a function pointer. A successful exploit redirects execution flow to attacker-controlled shellcode embedded in the document, achieving remote code execution.
Protection:
- Apply the latest security updates from Microsoft as soon as they are released.
- Configure systems to block or quarantine suspicious Word documents.
- Educate users to avoid opening files from untrusted sources.
- Monitor system logs for unusual activity and enforce the principle of least privilege for Office applications.
Impact:
Successful exploitation allows an unauthorized attacker to execute arbitrary code locally, leading to a complete system compromise with full control over the affected machine.
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Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
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