High severity · published Oct 13, 2026
CVE-2026-77910
Microsoft Exchange Server Elevation of Privilege Vulnerability
8.8
CVSS
0.9%
EPSS
No
On KEV
Description
Incorrect authorization in Microsoft Exchange Server allows an authorized attacker to elevate privileges over a network.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.9% · higher than 59% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
ME
Microsoft Exchange Server 2016 Cumulative Update 23 · Microsoft
15.01.0.0 before 15.01.2507.077 · source: vendor
ME
Microsoft Exchange Server 2019 Cumulative Update 14 · Microsoft
15.02.0.0 before 15.02.1544.050 · source: vendor
ME
Microsoft Exchange Server 2019 Cumulative Update 15 · Microsoft
15.02.0.0 before 15.02.1748.055 · source: vendor
ME
Microsoft Exchange Server Subscription Edition RTM · Microsoft
15.02.0.0 before 15.02.2562.056 · source: vendor
Affected product
ME
Microsoft Exchange Server 2016 Cumulative Update 23
Microsoft
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-77910
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-77910
vendor-advisory
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-77910
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