CVE-2026-62911: Microsoft Exchange Server Elevation of Privilege Vulnerability

Severity: high (CVSS 8.0 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.7% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-08-11 · updated 2026-10-30
Weakness: CWE-294

Description

Authentication bypass by capture-replay 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 15.02.2562.046 — fixed in 15.02.2562.046
Microsoft Exchange Server 2016 Cumulative Update 23: from 15.01.0.0 before 15.01.2507.072 — fixed in 15.01.2507.072
Microsoft Exchange Server 2019 Cumulative Update 14: from 15.02.0.0 before 15.02.1544.044 — fixed in 15.02.1544.044
Microsoft Exchange Server 2019 Cumulative Update 15: from 15.02.0.0 before 15.02.1748.049 — fixed in 15.02.1748.049
Microsoft Exchange Server Subscription Edition RTM: from 15.02.0.0 before 15.02.2562.046 — fixed in 15.02.2562.046

How to fix

Upgrade to a fixed version: Microsoft Exchange Server Subscription Edition 15.02.2562.046; Microsoft Exchange Server 2016 Cumulative Update 23 15.01.2507.072; Microsoft Exchange Server 2019 Cumulative Update 14 15.02.1544.044; Microsoft Exchange Server 2019 Cumulative Update 15 15.02.1748.049; Microsoft Exchange Server Subscription Edition RTM 15.02.2562.046. Check the vendor advisory for mitigations.

References

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