CVE-2025-59249: Microsoft Exchange Server Elevation of Privilege Vulnerability

Severity: high (CVSS 8.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.8% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-10-14 · updated 2026-10-18
Weakness: CWE-1390

Description

Weak authentication in Microsoft Exchange Server allows an authorized attacker to elevate privileges over a network.

Affected products

Microsoft Exchange Server: 2016-cumulative_update_1, 2016-cumulative_update_10, 2016-cumulative_update_11, 2016-cumulative_update_12, 2016-cumulative_update_13, 2016-cumulative_update_14 (+29); 2016, 2019
Microsoft Exchange Server Subscription Edition: before 15.02.2562.029 — fixed in 15.02.2562.029
Microsoft Exchange Server 2016 Cumulative Update 23: from 15.01.0.0 before 15.01.2507.061 — fixed in 15.01.2507.061
Microsoft Exchange Server 2019 Cumulative Update 14: from 15.02.0.0 before 15.02.1544.036 — fixed in 15.02.1544.036
Microsoft Exchange Server 2019 Cumulative Update 15: from 15.02.0.0 before 15.02.1748.039 — fixed in 15.02.1748.039
Microsoft Exchange Server Subscription Edition RTM: from 15.02.0.0 before 15.02.2562.029 — fixed in 15.02.2562.029

How to fix

Upgrade to a fixed version: Microsoft Exchange Server Subscription Edition 15.02.2562.029; Microsoft Exchange Server 2016 Cumulative Update 23 15.01.2507.061; Microsoft Exchange Server 2019 Cumulative Update 14 15.02.1544.036; Microsoft Exchange Server 2019 Cumulative Update 15 15.02.1748.039; Microsoft Exchange Server Subscription Edition RTM 15.02.2562.029. Check the vendor advisory for mitigations.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-59249

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