All vulnerabilities
CVE-2026-77910

Microsoft Exchange Server Elevation of Privilege Vulnerability

Microsoft Microsoft Exchange Server 2016 Cumulative Update 23Applications & CMS
Open in ThreatlineRecord JSON
CVSS
8.8High
ExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)0.77%Chance of exploitation activity in the next 30 days, higher than 54% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in15.01.2507.077Also 15.02.1544.050, 15.02.1748.055 and 1 moreCVE List
Published13 Oct 2026Updated 23 Oct 2026CVE List

What fixes it

  • 15.01.2507.077Microsoft Exchange Server 2016 Cumulative Update 23CVE List
  • 15.02.1544.050Microsoft Exchange Server 2019 Cumulative Update 14CVE List
  • 15.02.1748.055Microsoft Exchange Server 2019 Cumulative Update 15CVE List
  • 15.02.2562.056Microsoft Exchange Server Subscription Edition RTMCVE List

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

Vendor and government advisories 1

Vendors that say their products are affected, and agencies that issued alerts. Check each for the fixed release of the product you run.

Reports 1

1 outlet mention it. Reports are not confirmation; each links to its source.

Description

Incorrect authorization in Microsoft Exchange Server allows an authorized attacker to elevate privileges over a network.

Text from CVE List

Affected versions 4

  • Microsoft Exchange Server 2016 Cumulative Update 23affected: 15.01.0.0 before 15.01.2507.077CVE List
  • Microsoft Exchange Server 2019 Cumulative Update 14affected: 15.02.0.0 before 15.02.1544.050CVE List
  • Microsoft Exchange Server 2019 Cumulative Update 15affected: 15.02.0.0 before 15.02.1748.055CVE List
  • Microsoft Exchange Server Subscription Edition RTMaffected: 15.02.0.0 before 15.02.2562.056CVE List

References 1