EUVD-2026-73307
GHSA-6hj5-28cq-px6j
Severity by source
AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Network-delivered document exploit requiring only victim file-open action; no attacker auth or special configuration needed; full code execution impact.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
3DescriptionCVE.org
Heap-based buffer overflow in Microsoft Office allows an unauthorized attacker to execute code over a network.
AnalysisAI
Heap-based buffer overflow in Microsoft Office allows unauthenticated remote attackers to execute arbitrary code on a victim's system when the victim opens a specially crafted Office document. Multiple product lines are affected, including Microsoft 365 Apps for Enterprise, Office LTSC 2021/2024, Office 2016/2019, and Mac variants of each. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | The attacker must deliver a malicious Office document to a victim and induce the victim to open or preview it in an affected version of Microsoft Office - this is the sole prerequisite (UI:R). … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.1 vector AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H reflects a classic Office document-based attack path: network-delivered, no attacker authentication required, low complexity, but requiring the victim to open a malicious file (UI:R). … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | Apply the vendor-released patches documented in the Microsoft Security Response Center advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-78505. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, identify and inventory all affected Microsoft Office installations across your environment, including Microsoft 365 Apps, Office LTSC 2021/2024, Office 2016/2019, and Mac deployments; simultaneously communicate internally that users should avoid opening suspicious documents until patches are deployed. …
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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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