EUVD-2026-44177
GHSA-f28p-7rm3-827g
Severity by source
AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
File must be opened locally by a victim (AV:L, UI:R) with no prior auth (PR:N); memory-corruption code execution yields full C/I/A impact in the user context (S:U).
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Lifecycle Timeline
2DescriptionCVE.org
Heap-based buffer overflow in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
AnalysisAI
Arbitrary code execution in Microsoft Excel (across Microsoft 365 Apps, Office 2019, Office LTSC 2021/2024, Office for Mac, and Office Online Server) arises from a heap-based buffer overflow (CWE-122) that triggers when a victim opens a maliciously crafted spreadsheet. The CVSS 3.1 vector (AV:L/AC:L/PR:N/UI:R) confirms this is a local, user-interaction-dependent file-format attack rather than a remote network exploit, yielding code execution in the context of the current user. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires a user to open or preview a specially crafted Excel workbook delivered by the attacker - the CVSS vector's UI:R makes victim interaction a hard prerequisite, and AV:L means the malicious file must be processed locally by the target's Excel install rather than exploited over the network. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | This is a genuine but not top-tier emergency. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker emails a weaponized .xlsx spreadsheet crafted to overflow Excel's heap parser, using a lure that entices the target to open it and dismiss Protected View. When the file is opened, the overflow corrupts heap memory and executes attacker-controlled code with the victim's privileges, establishing a foothold for follow-on payloads. … |
| Remediation | Apply the Microsoft security update for CVE-2026-55029 as documented in the MSRC advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55029 (Patch available per vendor advisory); for click-to-run installs of Microsoft 365 Apps and Office LTSC this arrives via the normal update channel, while Office Online Server and MSI-based Office 2016/2019 require the corresponding cumulative/security package for the affected build. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, conduct inventory of all Microsoft Office installations across the organization to identify systems running affected versions and issue security alert to users to avoid opening unsolicited spreadsheet attachments pending patch deployment. …
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Arbitrary code execution in Microsoft PowerPoint (and the broader Microsoft Office/365 suite on Windows and macOS) arise
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Local code execution in Microsoft Office PowerPoint (CWE-122 heap-based buffer overflow) lets an unauthorized attacker r
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Local code execution in Microsoft Office (2016, 2019, LTSC 2021/2024, Microsoft 365 Apps, and Office for Mac 2021/2024)
Same weakness CWE-122 – Heap-based Buffer Overflow
View allSame technique Heap Overflow
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External POC / Exploit Code
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