CVE-2026-88155 in SharePoint Server
Summary
by MITRE • 10/14/2026
Heap-based buffer overflow in Microsoft Office SharePoint allows an authorized attacker to execute code over a network.
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Analysis
by VulDB Data Team • 10/14/2026
The vulnerability described constitutes a critical security flaw within the Microsoft Office SharePoint environment, 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 on the heap, potentially overwriting adjacent memory structures or control data such as function pointers and return addresses. In the context of SharePoint, this flaw is triggered through specific interactions with document processing components or web services that handle untrusted input without adequate bounds checking. The severity of this vulnerability is significantly amplified by its network-accessible nature, allowing an attacker to exploit it remotely over a network connection rather than requiring local physical access or direct user interaction beyond initial vectoring.
An authorized attacker can leverage this heap-based buffer overflow to achieve arbitrary code execution on the target system. By carefully crafting malicious input that exploits the memory corruption, the attacker gains the ability to execute shellcode within the security context of the affected application process. Since SharePoint services often run with elevated privileges or have access to sensitive organizational data and infrastructure components, successful exploitation can lead to a complete compromise of the server hosting the service. This allows the attacker to install malware, create new user accounts for persistent access, exfiltrate confidential documents stored within the SharePoint environment, or use the compromised system as a pivot point to attack other internal network resources.
From an industry standards perspective, this vulnerability aligns with CWE-122, which defines heap-based buffer overflow, and is categorized under MITRE ATT&CK technique T1059, Command and Scripting Interpreter, specifically when used for initial access or lateral movement via remote code execution. The attack vector falls under Remote Code Execution (RCE), a high-severity category that consistently ranks among the most dangerous vulnerabilities in enterprise environments due to its potential for widespread impact with minimal effort from the adversary. The requirement for authorization suggests that while the attacker must have valid credentials, this does not mitigate the risk significantly as compromised user accounts are common vectors for such attacks.
Mitigation strategies should focus on immediate patching and network segmentation. Organizations running affected versions of Microsoft Office SharePoint must apply the latest security updates provided by Microsoft to address the underlying memory management flaws in the software components involved. Additionally, implementing strict input validation at the application layer can help prevent malformed data from reaching vulnerable functions, although this is often a secondary defense compared to patching. Network-level controls such as firewalls and intrusion detection systems should be configured to monitor for anomalous traffic patterns indicative of exploitation attempts, particularly those involving unusual heap allocations or memory access violations. Restricting SharePoint service exposure to only necessary internal networks further reduces the attack surface available to potential adversaries.