Microsoft Office Outlook Remote Code Execution Vulnerability

CVE-2026-70291 is a remote code execution vulnerability in Microsoft Office Outlook (rated Critical, CVSS 9.8).

1 version

Microsoft id: CVE-2026-70291
Products: Microsoft Office Outlook
Severity: Critical
Impact: Remote Code Execution
CVSS: 9.8
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/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-Oct
Assigned by: Microsoft
Weakness: CWE-122: Heap-based Buffer Overflow
MSRC revision: 1.2
Status pages: Outlook status
First captured by us: 13 Nov 2026, 15:11 UTC (from our first import of this list)
Microsoft last modified: 10 Nov 2026, 16:00 UTC
Source: Security updates · open the original at Microsoft

Microsoft's revision notes

Revision 1.0, 2026-10-13: Information published.
Revision 1.1, 2026-10-15: Microsoft is announcing the availability of the security updates for Microsoft Office for Mac.
Revision 1.2, 2026-11-10: Updated an acknowledgement. This is an informational change only.

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

Security updates, 16:00 UTC, 10 Nov

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

First version we captured · 15:11 UTC, 13 Nov
The text as we first saw it
Seen by us 15:11 UTC, 13 Nov · Microsoft's timestamp 16:00 UTC, 10 Nov · Microsoft's page