CVE-2026-69626 in Office
Summary
by MITRE • 09/09/2026
Buffer over-read in Microsoft Office allows an unauthorized attacker to disclose information over a network.
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Analysis
by VulDB Data Team • 09/09/2026
The vulnerability described constitutes a buffer over-read flaw within the core processing components of Microsoft Office, specifically affecting how the application handles certain data structures or file formats during parsing operations. This type of memory corruption issue arises when the software reads beyond the allocated boundaries of a buffer in system memory. Unlike more severe exploitation vectors that allow arbitrary code execution, this specific defect primarily facilitates information disclosure rather than remote command execution. The root cause typically involves insufficient validation of input length parameters before copying or reading data into fixed-size buffers, leading to the exposure of adjacent memory contents which may contain sensitive operational data, cryptographic keys, user credentials, or internal application states that were not intended for external access.
From an architectural perspective, this flaw represents a classic violation of safe memory management practices where boundary checks are either missing or incorrectly implemented. When Microsoft Office processes maliciously crafted documents or files containing specially constructed payloads, the parser fails to verify that the requested read operation stays within the valid limits of the buffer. Consequently, the application retrieves data from neighboring memory locations. This behavior aligns with Common Weakness Enumeration category CWE-126, which defines Buffer Over-read as a condition where software reads past the end of an allocated buffer. The presence of this weakness indicates a gap in input validation logic within the document rendering engine or related subsystems responsible for interpreting complex file structures such as those found in Word documents, Excel spreadsheets, or PowerPoint presentations that utilize embedded objects or specific encoding schemes.
The operational impact of this vulnerability is centered on unauthorized information disclosure rather than system compromise through code execution. An attacker who can trick a user into opening a maliciously crafted document over a network connection could potentially extract sensitive data from the victim's memory space. This disclosed information might include session tokens, cached passwords, or other proprietary data stored in the application’s working memory. While this does not directly grant control over the target system, it serves as a critical reconnaissance step that can be leveraged for further attacks such as credential theft, social engineering, or lateral movement within an enterprise network environment. The attack vector is classified under remote exploitation via network services, specifically targeting users who interact with untrusted documents received through email or file sharing platforms.
In terms of threat modeling and adversary behavior, this vulnerability maps to the ATT&CK technique T1005, which covers Data from Local System Retrieval. Attackers utilize such flaws to gather intelligence about the target environment without triggering immediate alarms associated with more aggressive exploitation methods like buffer overflows leading to shellcode injection. The stealthy nature of information disclosure makes it particularly dangerous in targeted attacks where maintaining persistence and avoiding detection are paramount for long-term access strategies. Organizations must recognize that even non-execution vulnerabilities pose significant risks by exposing critical assets and facilitating subsequent phases of an attack chain, including privilege escalation or data exfiltration if combined with other weaknesses.
Mitigation efforts should prioritize the immediate application of vendor-provided security patches to update Microsoft Office components to versions where this buffer boundary check has been corrected. Administrators must ensure that automatic updates are enabled for all endpoints running affected software versions. Additionally, implementing strict email filtering policies and sandboxing mechanisms can help detect and block malicious documents before they reach end-user systems. User awareness training is also essential to reduce the likelihood of users opening unsolicited attachments from unknown sources. For environments where patching cannot be immediately applied, network segmentation and application whitelisting can provide additional layers of defense by restricting how Office applications interact with external resources and limiting their ability to process untrusted inputs directly in production contexts.