EUVD-2026-35646
GHSA-9jgc-vw8w-2xv8
Severity by source
AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/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
Integer underflow (wrap or wraparound) in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
AnalysisAI
Local code execution in Microsoft Office Excel results from an integer underflow (CWE-122 heap-based) that allows an unauthorized attacker to run arbitrary code in the context of the user opening a crafted spreadsheet. The CVSS 7.8 score reflects local attack vector with required user interaction, and 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 a specifically crafted Excel document (UI:R) on a vulnerable, unpatched installation of Microsoft Office Excel - the malicious file must reach the user, and the user must open it outside of Protected View (or be coaxed into clicking 'Enable Editing'), which is the practical gating factor. … 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 describes a local-vector, low-complexity, no-privilege issue that requires user interaction - consistent with the typical Office document-open exploitation pattern where 'local' means the malicious file is processed on the victim host. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker emails a target user a weaponized .xlsx or .xls workbook (or hosts it on a SharePoint/OneDrive link) crafted so that a length field underflows during parsing, producing an undersized heap allocation that is then overwritten with attacker-controlled bytes. When the user opens the file and dismisses Protected View, the heap corruption is steered into control-flow hijacking that executes shellcode in the Excel process, giving the attacker code execution as the logged-in user. … |
| Remediation | Apply the Microsoft security update for Excel referenced in the MSRC advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-45469 as the primary fix; exact patched build numbers are published in that advisory and should be matched to your Office channel (Current, Monthly Enterprise, Semi-Annual, or LTSC). … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours: Issue security alert blocking Excel file downloads from untrusted external sources and train users to reject unexpected spreadsheets. …
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Same weakness CWE-122 – Heap-based Buffer Overflow
View allSame technique Buffer Overflow
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External POC / Exploit Code
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