Use of uninitialized resource in Microsoft products - CVE-2026-78519
Published: September 9, 2026
Vulnerability identifier: #VU148237
CSH Severity: High
CVSS v4: 8.4 [CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-78519
CWE-ID: CWE-908
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to execute arbitrary code.
The vulnerability exists due to use of an uninitialized resource in Microsoft Office Outlook when processing a specially crafted email. A remote attacker can send a specially crafted email to a victim to execute arbitrary code.
Exploitation requires the victim to open the email or for Outlook to display its preview.
Affected software
Microsoft 365 Apps for Enterprise
Microsoft Outlook
Microsoft Office
Microsoft Outlook
Microsoft Office
How to mitigate CVE-2026-78519
Install security update from vendor's website.
Microsoft 365 Apps for Enterprise - update to 16.0.20326.20138
Microsoft Outlook - update to 16.0.5569.1000
Microsoft Office - addressed in versions 16.0.10417.20207, 16.0.14334.20906, 16.0.17932.20976
Microsoft Outlook - update to 16.0.5569.1000
Microsoft Office - addressed in versions 16.0.10417.20207, 16.0.14334.20906, 16.0.17932.20976