Microsoft Office Word Remote Code Execution Vulnerability

CVE-2026-63518 is a remote code execution vulnerability in Microsoft Office Word (rated Critical, CVSS 7.8).

1 version

Microsoft id: CVE-2026-63518
Products: Microsoft Office Word
Severity: Critical
Impact: Remote Code Execution
CVSS: 7.8
CVSS vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
Exploited: No
Publicly disclosed: No
Exploitability: Exploitation Less Likely
Customer action required: Yes
Release: 2026-Aug
Assigned by: Microsoft
Weakness: CWE-122: Heap-based Buffer Overflow
MSRC revision: 1.1
Status pages: Microsoft 365 apps status
First captured by us: 13 Nov 2026, 15:07 UTC (from our first import of this list)
Microsoft last modified: 17 Aug 2026, 14:00 UTC
Source: Security updates · open the original at Microsoft

Microsoft's revision notes

Heap-based buffer overflow in Microsoft Office Word allows an unauthorized attacker to execute code locally.

Security updates, 14:00 UTC, 17 Aug

One version so far. If Microsoft edits it, each change shows here with what was removed and added.

First version we captured · 15:07 UTC, 13 Nov
The text as we first saw it
Seen by us 15:07 UTC, 13 Nov · Microsoft's timestamp 14:00 UTC, 17 Aug · Microsoft's page