What’s Vulnerable › Vulnerabilities

CVE-2019-1204: Microsoft Outlook Elevation of Privilege Vulnerability

• Severity: medium (CVSS 4.3 v3.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 4.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2019-08-14 · updated 2026-06-17
• Weakness: CWE-20

Description

An elevation of privilege vulnerability exists when Microsoft Outlook initiates processing of incoming messages without sufficient validation of the formatting of the messages. An attacker who successfully exploited the vulnerability could attempt to force Outlook to load a local or remote message store (over SMB). To exploit the vulnerability, the attacker could send a specially crafted email to a victim. Outlook would then attempt to open a pre-configured message store contained in the email upon receipt of the email. This update addresses the vulnerability by ensuring Office fully validates incoming email formatting before processing message content.

Affected products

• Microsoft Office: 2019
• Microsoft Office 365 ProPlus: all versions
• Microsoft Outlook: 2010-sp2, 2013-sp1, 2016
• Microsoft Outlook 2010 Service Pack 2: from 13.0.0.0 before publication — fixed in publication
• Microsoft Outlook 2013 Service Pack 1: from 15.0.0.0 before publication — fixed in publication
• Microsoft Office: from 19.0.0 before https://aka.ms/OfficeSecurityReleases — fixed in https://aka.ms/OfficeSecurityReleases
• Microsoft Office 365 ProPlus: from 16.0.0 before publication — fixed in publication
• Microsoft Outlook 2016 for Mac: from 16.0.0.0 before publication — fixed in publication

How to fix

Upgrade to a fixed version: Microsoft Outlook 2010 Service Pack 2 publication; Microsoft Outlook 2013 Service Pack 1 publication; Microsoft Office https://aka.ms/OfficeSecurityReleases; Microsoft Office 365 ProPlus publication; Microsoft Outlook 2016 for Mac publication. Check the vendor advisory for mitigations.

References

• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2019-1204
• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2019-1204

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