CVE-2026-55009

Microsoft Exchange Server Elevation of Privilege Vulnerability

State: Published
Severity: 7.8 High
Published: Jul 14, 2026
Updated: Nov 1, 2026
Reserved: Jun 16, 2026

Description

Deserialization of untrusted data in Microsoft Exchange Server allows an authorized attacker to elevate privileges locally.

Scores

CVSS	Score	Vector	Source
3.1	7.8 High	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C	microsoft

Weaknesses

CWE-502 Deserialization of Untrusted Data

Affected Products

Product	Versions
Microsoft Exchange Server 2016 Cumulative Update 23Microsoft	15.01.0.0 to before 15.01.2507.071Affected
Microsoft Exchange Server 2019 Cumulative Update 14Microsoft	15.02.0.0 to before 15.02.1544.043Affected
Microsoft Exchange Server 2019 Cumulative Update 15Microsoft	15.02.0.0 to before 15.02.1748.048Affected
Microsoft Exchange Server Subscription Edition RTMMicrosoft	15.02.0.0 to before 15.02.2562.045Affected

References

Microsoft Exchange Server Elevation of Privilege Vulnerabilityvendor-advisorypatch

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