Review reviewHigh

CVE-2026-55005

Microsoft Microsoft Exchange Server 2016 Cumulative Update 23, Microsoft Exchange Server 2019 Cumulative Update 14, Microsoft Exchange Server 2019 Cumulative Update 15

Heap-based buffer overflow in Microsoft Exchange Server allows an authorized attacker to execute code over a network.

PRIORITY ASSESSMENT

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV

Exploit probability0.66%

Technical severityCVSS 8.8

Heap-based buffer overflow in Microsoft Exchange Server allows an authorized attacker to execute code over a network.

Product: Microsoft Microsoft Exchange Server 2016 Cumulative Update 23, Microsoft Exchange Server 2019 Cumulative Update 14, Microsoft Exchange Server 2019 Cumulative Update 15
Affected versions: >= 15.01.0.0 < 15.01.2507.071, >= 15.02.0.0 < 15.02.1544.043, >= 15.02.0.0 < 15.02.1748.048, >= 15.02.0.0 < 15.02.2562.045, 2016, 2019, < 15.02.2562.045
Fixed versions: 15.02.2562.045

Confirm exposure before applying a vendor-supported change.

1
Identify
Confirm that Microsoft Microsoft Exchange Server 2016 Cumulative Update 23, Microsoft Exchange Server 2019 Cumulative Update 14, Microsoft Exchange Server 2019 Cumulative Update 15 and an affected version are present.
2
Prioritize
Combine exploitation signals with asset exposure and business criticality.
3
Remediate
Follow the vendor advisory or supported update path and preserve rollback options.
4
Verify
Recheck the version, service health, access paths, and relevant logs.