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TI-2026-72374 Aliases CVE-2026-77910GHSA-8324-3q3h-54w9

Microsoft Exchange Server flaw lets attackers gain higher privileges

Priority MEDIUM 42CWE-863Published · Updated

Key facts

Attack vector
Network
Privileges required
Low
User interaction
None
Attack complexity
Low
Impact type
Security bypass
Confidentiality · integrity · availability
High · High · High
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-863.

Summary

Microsoft Exchange Server 2016 Cumulative Update 23 from 15.01.0.0 before 15.01.2507.077, 2019 Cumulative Update 14 from 15.02.0.0 before 15.02.1544.050, 2019 Cumulative Update 15 from 15.02.0.0 before 15.02.1748.055, and Subscription Edition RTM from 15.02.0.0 before 15.02.2562.056 are affected. Incorrect authorization (CWE-863) lets an authorized attacker over the network gain higher privileges. The attacker needs low privileges and no user interaction.

Written with Claude Haiku 5.5 from the sources below · 2026-10-28

Description from the CNA

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

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00867 58th percentileScored 2026-11-07
Fix Fixed Microsoft Exchange Server 2016 Cumulative Update 23 (Microsoft): 15.01.2507.077Microsoft Exchange Server 2019 Cumulative Update 14 (Microsoft): 15.02.1544.050+2 more products

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
MicrosoftMicrosoft Exchange Server 2016 Cumulative Update 2315.01.0.0 to before 15.01.2507.07715.01.2507.077Patch availableCNA
MicrosoftMicrosoft Exchange Server 2019 Cumulative Update 1415.02.0.0 to before 15.02.1544.05015.02.1544.050Patch availableCNA
MicrosoftMicrosoft Exchange Server 2019 Cumulative Update 1515.02.0.0 to before 15.02.1748.05515.02.1748.055Patch availableCNA
MicrosoftMicrosoft Exchange Server Subscription Edition RTM15.02.0.0 to before 15.02.2562.05615.02.2562.056Patch availableCNA
  • Microsoft Exchange Server 2016 Cumulative Update 23 VendorMicrosoft Affected 15.01.0.0 to before 15.01.2507.077 Fixed in 15.01.2507.077 Patch available CNA
  • Microsoft Exchange Server 2019 Cumulative Update 14 VendorMicrosoft Affected 15.02.0.0 to before 15.02.1544.050 Fixed in 15.02.1544.050 Patch available CNA
  • Microsoft Exchange Server 2019 Cumulative Update 15 VendorMicrosoft Affected 15.02.0.0 to before 15.02.1748.055 Fixed in 15.02.1748.055 Patch available CNA
  • Microsoft Exchange Server Subscription Edition RTM VendorMicrosoft Affected 15.02.0.0 to before 15.02.2562.056 Fixed in 15.02.2562.056 Patch available CNA

Remediation

Update Microsoft Exchange Server 2016 Cumulative Update 23 to 15.01.2507.077, 2019 Cumulative Update 14 to 15.02.1544.050, 2019 Cumulative Update 15 to 15.02.1748.055, and Subscription Edition RTM to 15.02.2562.056.

Written with Claude Haiku 5.5 from the sources below · 2026-10-28

  • Fix · CNA Microsoft Exchange Server 2016 Cumulative Update 23 (Microsoft) Fixed in 15.01.2507.077
  • Fix · CNA Microsoft Exchange Server 2019 Cumulative Update 14 (Microsoft) Fixed in 15.02.1544.050
  • Fix · CNA Microsoft Exchange Server 2019 Cumulative Update 15 (Microsoft) Fixed in 15.02.1748.055
  • Fix · CNA Microsoft Exchange Server Subscription Edition RTM (Microsoft) Fixed in 15.02.2562.056

Timeline

  1. 2026-10-13 Threatist record created from CVE-2026-77910
  2. 2026-10-13 Alias added: GHSA-8324-3q3h-54w9
  3. 2026-10-14 CISA SSVC decision points changed
  4. 2026-10-14 Priority changed: LOW → MEDIUM

References

Patch 1

  • TI-2026-42212 Microsoft SharePoint Remote Code Execution Vulnerability KEVCVSS 3.1CRITICAL 9.8
  • TI-2026-37256 Microsoft SharePoint Remote Code Execution Vulnerability KEVCVSS 3.1CRITICAL 9.8
  • TI-2026-26194 Windows Internet Key Exchange (IKE) Service Extensions Remote Code Execution Vulnerability KEVCVSS 3.1CRITICAL 9.8
  • TI-2026-16982 Microsoft SharePoint Remote Code Execution Vulnerability KEVCVSS 3.1CRITICAL 9.8
  • TI-2025-36863 Windows Server Update Service (WSUS) Remote Code Execution Vulnerability KEVCVSS 3.1CRITICAL 9.8
  • TI-2025-33671 Microsoft SharePoint Server Remote Code Execution Vulnerability KEVCVSS 3.1CRITICAL 9.8
See all 18045 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences