EUVD-2026-44203
GHSA-q5m6-w3x7-pm25
Severity by source
AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Local file-parsing overflow needing victim to open a crafted document (AV:L, UI:R), no attacker privileges (PR:N), yielding full code execution in user context (C/I/A:H).
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
Local code execution in Microsoft Excel arises from a heap-based buffer overflow (CWE-122) that an attacker triggers by luring a victim into opening a maliciously crafted spreadsheet, yielding attacker code in the user's security context. It affects a broad Office family including Microsoft 365 Apps for Enterprise, Excel 2016, Office 2019, Office LTSC 2021/2024, the macOS editions, and Office Online Server. …
Unlock full vulnerability intelligence
- Risk assessment & exploitation conditions
- Attack chain visualization
- Remediation with exact patch versions
- Threat intelligence from 22 sources
- Personal watchlist & email alerts
Free forever · No credit card required
Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires a user to open a maliciously crafted Excel document (UI:R in the CVSS vector) in an affected build of Excel/Office, so it is not remotely triggerable without victim action. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.1 vector (AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H, score 7.8 HIGH) describes a client-side vulnerability: the local attack vector combined with required user interaction means exploitation depends on a victim opening a crafted file, not on remote network reachability. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker emails a finance employee a crafted .xlsx/.xls spreadsheet that appears to be an invoice; when the victim opens it in Excel, the malformed structure overflows a heap buffer during parsing and executes attacker-supplied code in the user's context. Because AV is local and UI is required, the attack hinges on social engineering rather than remote reach, and no public exploit code has been identified at time of analysis. |
| Remediation | Patch available per vendor advisory - apply the Microsoft update for CVE-2026-55053 documented at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55053, ensuring Microsoft 365 Apps, Office 2019/2016, the LTSC 2021/2024 channels, the macOS editions, and Office Online Server all receive their respective fixed builds; the input does not specify an exact fixed version number, so pull the precise build from the MSRC guide per product/channel. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, identify and inventory all systems running affected Microsoft Office versions (Microsoft 365 Apps for Enterprise, Excel 2016, Office 2019, Office LTSC 2021/2024, Office Online Server, and macOS editions). …
Sign in for detailed remediation steps and compensating controls.
Threat intelligence, references, and detailed analysis are available after sign-in.
Local code execution in Microsoft Word (and Office/SharePoint components that render Word content) stems from an integer
Local code execution in Microsoft Office (2016, 2019, LTSC 2021/2024, Microsoft 365 Apps, and the macOS editions) arises
Arbitrary code execution in Microsoft Office Word (and the broader Office/365/SharePoint family) arises from a stack-bas
Local code execution in Microsoft Office (including Microsoft 365 Apps for Enterprise, Office 2016/2019, and Office LTSC
Local code execution in Microsoft Word (part of Microsoft 365 Apps, Office 2019, Office LTSC 2021/2024, and Office for M
Local arbitrary code execution in Microsoft Office (2016, 2019, LTSC 2021/2024, Microsoft 365 Apps for Enterprise, and O
Arbitrary code execution in Microsoft PowerPoint (and the broader Microsoft Office/365 suite on Windows and macOS) arise
Local code execution in Microsoft Office PowerPoint (including Microsoft 365 Apps, Office 2019, Office LTSC 2021/2024, a
Local code execution in Microsoft Office PowerPoint (CWE-122 heap-based buffer overflow) lets an unauthorized attacker r
Local code execution in Microsoft Word (and the wider Microsoft Office / Microsoft 365 Apps family) lets an unauthorized
Local code execution in Microsoft Office (2016, 2019, LTSC 2021/2024, Microsoft 365 Apps for Enterprise, and Office for
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
View allShare
External POC / Exploit Code
Leaving vuln.today