CVE-2026-102857: Heap buffer overflow in Microsoft Office Visio · ZeroHour

CVE-2026-102857

large

Heap buffer overflow in Microsoft Office Visio

CVSS 3.1

8.8 high

EPSS

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Published

Oct 13, 2026 (3d ago)

Modified

Oct 15, 2026

AI analysis

CVE-2026-102857 is a heap-based buffer overflow, also associated with an off-by-one error, in Microsoft Office Visio. A remote, unauthenticated attacker can trigger it over the network if a user opens a malicious Visio file or similar crafted content (CVSS 3.1 8.8; user interaction required, low attack complexity). Successful exploitation can run arbitrary code with the user's privileges and fully compromise confidentiality, integrity, and availability on that system. Anyone who uses affected Microsoft Office Visio and opens untrusted diagrams is at risk; version ranges were not listed in the supplied data. It is not on the CISA KEV list, and no public proof-of-concept is known.

What to do: Install Microsoft's October 2026 security updates for Office/Visio as soon as they are available for your channel, and confirm Visio is no longer vulnerable after patching. Until then, do not open Visio files from untrusted sources and use email and web filtering to block unexpected .vsdx and related Visio attachments.

Affected

Microsoft Office Visio

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Estimated exposure

largemillions of enterprise Visio installations (order of magnitude; exact count unknown) — Visio is a widely licensed Microsoft 365/Office add-on used mainly in enterprises rather than on every Office seat or as an internet-exposed service; public install counts are not in the advisory, so this is an order-of-magnitude estimate…

Order-of-magnitude estimate by the model from install counts, market share and public scan data it knows; verify before quoting.

Description

Heap-based buffer overflow in Microsoft Office Visio allows an unauthorized attacker to execute code over a network.

Vendors: microsoft
Products: 365 apps, office 2021, office 2024
Weakness: CWE-122, CWE-193
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

NVD CVE.org GitHub PoCs EPSS (—)

CVE-2026-102857

In the news1 stories

The October 2026 Security Update Review