EUVD-2026-56459
GHSA-5wr6-m8x4-v27m
Severity by source
AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
File parsed locally (AV:L, UI:R); attacker needs no system account (PR:N); successful exploitation yields full code execution in victim context (C:H/I:H/A:H).
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
3DescriptionCVE.org
Out-of-bounds write in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
AnalysisAI
Out-of-bounds write (CWE-787) in Microsoft Office Excel enables local code execution when a user opens a specially crafted Excel file, yielding full confidentiality, integrity, and availability impact at CVSS 7.8. The attack is file-delivery based - typical phishing or drive-by download - requiring no system privileges from the attacker but requiring the victim to open the malicious document. No public exploit code or CISA KEV listing has been identified at time of analysis.
Technical ContextAI
CWE-787 (Out-of-Bounds Write) describes a memory corruption class in which a program writes data past the end of an allocated buffer. In Excel's file parser, a malformed Excel document can trigger this condition, potentially corrupting adjacent memory structures such as virtual function tables or return addresses. This class of vulnerability in file-format parsers is well-understood as a reliable path to arbitrary code execution because the attacker controls both the input data and, through the corruption, the eventual execution flow. The affected product is Microsoft Office Excel; exact build numbers and CPE strings were not enumerated in the available intelligence data.
RemediationAI
Apply the update provided by Microsoft via Windows Update, Microsoft Update Catalog, or enterprise patch management tooling; the MSRC advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-68806 is the authoritative source for the specific package versions and update KB numbers. An exact patched version number was not available in the data provided and should be verified from the advisory before closing remediation tickets. As a compensating control prior to patching, configure Microsoft Office Protected View to open files from the internet and email attachments in read-only mode, which prevents automatic parser execution of potentially malicious content - note this does not block exploitation if a user manually enables editing. Deploying email gateway policies to quarantine or strip Excel attachments from untrusted external senders reduces delivery risk with the trade-off of workflow friction for legitimate file sharing.
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Same weakness CWE-787 – Out-of-bounds Write
View allSame technique Buffer Overflow
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External POC / Exploit Code
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