CVE-2026-102856 in Visio
Summary
by MITRE • 10/13/2026
Heap-based buffer overflow in Microsoft Office Visio allows an unauthorized attacker to execute code over a network.
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Analysis
by VulDB Data Team • 10/13/2026
The vulnerability described constitutes a critical security flaw within Microsoft Office Visio, specifically manifesting as a heap-based buffer overflow. This type of memory corruption error occurs when a program writes data beyond the allocated boundaries of a buffer located in the computer's random access memory, known as the heap. In the context of Visio, this defect is triggered by processing specially crafted files or network traffic that contains malformed input data. The attacker leverages this flaw to overwrite adjacent memory locations with arbitrary values, which can include executable code pointers. Because the vulnerability allows for remote code execution over a network, it represents a significant threat vector where an unauthenticated user could potentially compromise the integrity and confidentiality of systems running affected versions of Visio without requiring any physical access or prior authentication credentials.
From a technical perspective, heap-based buffer overflows are particularly dangerous because they can be exploited to hijack control flow within the application process. By carefully crafting the input data, an attacker can manipulate function pointers stored in memory structures such as virtual method tables (vtables) or exception handling records. When these corrupted pointers are dereferenced by the Visio application during normal operation, execution is redirected to shellcode injected into the heap space. This mechanism allows for arbitrary code execution with the privileges of the user running the vulnerable software. The ability to execute code remotely makes this vulnerability highly attractive to threat actors who seek to establish persistent access or deploy additional malware payloads on targeted systems without direct interaction from the victim, aside from opening a malicious file or visiting a compromised webpage that triggers the rendering engine within Visio.
The operational impact of this vulnerability is severe, potentially leading to full system compromise. An attacker gaining code execution through this flaw can install programs, view, change, or delete data, and create new accounts with full user rights. In enterprise environments where Visio is used for network diagrams, infrastructure mapping, or technical documentation, the presence of such a vulnerability poses a risk not only to individual workstations but also to the broader organizational security posture if lateral movement occurs from an initially compromised endpoint. The remote nature of the exploit means that social engineering tactics, such as phishing emails containing malicious Visio files, are highly effective delivery mechanisms. Once executed, the malware can exfiltrate sensitive intellectual property contained within diagrams or serve as a foothold for further attacks against internal network resources.
To mitigate this risk, organizations must ensure that all instances of Microsoft Office Visio are updated to the latest version provided by Microsoft, which includes patches addressing these memory corruption issues. Security teams should also implement application control policies to restrict the execution of untrusted scripts and binaries, thereby limiting the impact if an exploit is successful. Additionally, deploying endpoint detection and response solutions can help identify anomalous behavior associated with heap exploitation attempts, such as unusual memory allocation patterns or unexpected process creation following file access events. Users must be educated on the risks of opening files from unknown sources, particularly those originating via email attachments or untrusted web downloads. Regular vulnerability scanning and patch management cycles are essential to maintain a secure baseline against known exploits like this one, which aligns with common weaknesses categorized under CWE-122 (Heap-based Buffer Overflow) in standard security taxonomies.