EUVD-2026-44174
GHSA-wx7g-r7w5-gv3h
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 the user (AV:L, UI:R) with no attacker privileges (PR:N); memory-corruption RCE yields full C/I/A impact within the user's 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
Integer overflow or wraparound in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
AnalysisAI
Local code execution in Microsoft Excel (spanning Microsoft 365 Apps for Enterprise, Excel 2016, Office 2019, Office LTSC 2021/2024, the macOS Office builds, and Office Online Server) arises from an integer overflow (CWE-190) triggered when the application parses a maliciously crafted spreadsheet. An unauthorized attacker who convinces a victim to open a booby-trapped file can run arbitrary code in the context of the current user, with full confidentiality, integrity, and availability impact per the 7.8 CVSS vector. …
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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 crafted Excel/Office file on an affected build - the CVSS vector's AV:L combined with UI:R means there is no remote network trigger; delivery depends on getting the file to the user and having them open it (and, in typical configurations, dismiss Protected View to reach full edit/parse paths). … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.1 vector CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H yields 7.8 (High): local attack vector, low complexity, no privileges required, but user interaction is mandatory. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker crafts a malicious Excel workbook whose internal size/count fields trigger the integer overflow and emails it to a target as a routine-looking attachment (e.g., an invoice or report). When the victim opens the file and, if prompted, exits Protected View, the corrupted allocation lets the attacker's payload execute as that user. … |
| Remediation | Patch available per vendor advisory: apply the Microsoft update for CVE-2026-55048 as documented at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55048, which provides fixed builds for each channel (Microsoft 365 Apps/Current Channel, the perpetual Office 2016/2019/LTSC 2021/2024 releases, the macOS builds, and Office Online Server). … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, identify and inventory all deployed Microsoft Excel instances (Microsoft 365 Apps for Enterprise, Excel 2016, Office 2019, Office LTSC 2021/2024, macOS Office, and Office Online Server) and issue immediate guidance to users to avoid opening Excel files from untrusted sources and defer access to non-critical spreadsheets until patched. …
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Same weakness CWE-190 – Integer Overflow or Wraparound
View allSame technique Buffer Overflow
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External POC / Exploit Code
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