EUVD-2026-44041
GHSA-vm8w-v83h-8752
Severity by source
AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
File must be opened locally so AV:L and UI:R; no prior privileges needed (PR:N); code runs as the user granting full C/I/A impact within an unchanged scope.
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
Use after free in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
AnalysisAI
Local code execution in Microsoft Excel (2016, Office 2019, Office LTSC 2021/2024, Microsoft 365 Apps, Office for Mac, and Office Online Server) arises from a use-after-free memory corruption (CWE-416) that an attacker triggers when a victim opens a maliciously crafted spreadsheet. Exploitation runs code in the context of the current user and requires user interaction (opening the file), with no public exploit identified at time of analysis. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires the victim to open an attacker-supplied malicious Excel workbook in a vulnerable build (UI:R) - the user interaction of opening the file is the mandatory trigger, and the attack is local (AV:L), not remotely exploitable over the network. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.1 base score of 7.8 (AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H) reflects high impact to confidentiality, integrity, and availability but constrained by a local attack vector and required user interaction - the 'local' vector here means the malicious file must be opened on the target, typically via phishing rather than remote network exploitation. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker emails a victim a crafted .xlsx/.xls spreadsheet (or hosts it on a shared/SharePoint location); when the user opens it in a vulnerable Excel build, the malformed structure triggers the use-after-free and executes attacker code with the user's privileges. Because the attack requires opening the file (UI:R) and runs locally, delivery is typically via phishing or a watering-hole document. … |
| Remediation | Patch available per vendor advisory: apply Microsoft's security update for CVE-2026-55948 across all affected Office channels via the MSRC update guide at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55948 (exact fixed build numbers are not specified in the provided data - retrieve them from the advisory for each channel such as Current Channel, Monthly Enterprise Channel, and LTSC). … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, inventory all systems running affected Microsoft Office versions (Excel 2016, Office 2019, Office LTSC 2021/2024, Microsoft 365 Apps, Office for Mac, Office Online Server) and issue a security alert instructing users to avoid opening unexpected spreadsheet attachments from untrusted sources. …
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Same weakness CWE-416 – Use After Free
View allSame technique Use After Free
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External POC / Exploit Code
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