CVE-2026-55049 in Office
Summary
by MITRE • 07/14/2026
Heap-based buffer overflow in Microsoft Office allows an unauthorized attacker to execute code locally.
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Analysis
by VulDB Data Team • 07/15/2026
A heap-based buffer overflow vulnerability in Microsoft Office presents a critical security risk that enables unauthorized attackers to execute arbitrary code on affected systems. This flaw resides within the memory management mechanisms of Microsoft Office applications, specifically exploiting how heap allocations are handled when processing specially crafted files or data inputs. The vulnerability stems from insufficient bounds checking during heap operations, allowing malicious data to overwrite adjacent memory regions in the heap space. When Office applications process malformed input through document parsing or file handling functions, the inadequate memory validation permits buffer overflows that can be leveraged for code execution.
The technical implementation of this vulnerability involves the exploitation of heap memory structures where Office applications allocate and manage memory blocks for various operations including document processing, object manipulation, and data rendering. Attackers craft malicious Office documents or files containing oversized data payloads that exceed the allocated buffer boundaries within heap memory allocations. This overflow can corrupt adjacent heap metadata, function pointers, or return addresses, enabling attackers to redirect execution flow to malicious code injected into the heap space. The vulnerability typically manifests when Office applications parse specific file formats such as word processing documents, spreadsheets, or presentation files that contain crafted elements designed to trigger the buffer overflow condition.
The operational impact of this vulnerability extends beyond simple privilege escalation as it provides attackers with a potent local execution vector that can be leveraged for persistent system compromise. Once successfully exploited, the attacker gains the ability to execute code with the privileges of the targeted user account, potentially leading to full system compromise or lateral movement within network environments. The vulnerability affects multiple Microsoft Office applications including Word, Excel, PowerPoint, and other components that utilize similar heap management patterns, making it a widespread concern across enterprise environments. Organizations face significant risk as these applications are widely deployed and frequently used for processing external documents, creating numerous attack vectors for threat actors to exploit.
Mitigation strategies for this vulnerability encompass multiple layers of defense including immediate patch deployment from Microsoft security updates, application whitelisting controls to restrict execution of untrusted Office files, and network segmentation to limit lateral movement capabilities. System administrators should implement the principle of least privilege by running Office applications with reduced privileges and employ enhanced memory protection mechanisms such as address space layout randomization and data execution prevention. Additionally, comprehensive monitoring and logging of Office application behavior can help detect anomalous file processing patterns that may indicate exploitation attempts. Security teams should also consider implementing email filtering solutions to prevent malicious Office documents from reaching end users, while maintaining regular security awareness training to reduce social engineering risks associated with file attachment exploitation. This vulnerability aligns with CWE-122 heap-based buffer overflow classifications and represents a technique commonly referenced in MITRE ATT&CK framework under the execution and privilege escalation tactics.