CVE-2025-26647 — Windows Kerberos Elevation of Privilege Vulnerability

Executive Summary

Improper input validation in Windows Kerberos allows an unauthorized attacker to elevate privileges over a network.

Overview

8.8

CVSS HIGH

Important

MS Severity

Not Exploited

MS Exploit Status

Less Likely

MS Exploit Likelihood

Category Elevation of Privilege

Released Apr 8 2025

Last Updated Apr 8 2025

Publicly Disclosed No

CISA KEV Not Listed

Known Exploits None Known

EPSS Score 0.01905 — 0.77039 percentile

NVD CVSS 8.8 HIGH — matches MSRC

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C

ATTACK VECTOR

Network

ATTACK COMPLEXITY

Low

PRIVILEGES REQUIRED

Low

USER INTERACTION

None

SCOPE

Unchanged

CONFIDENTIALITY

High

INTEGRITY

High

AVAILABILITY

High

EXPLOIT CODE MATURITY

Unproven

REMEDIATION LEVEL

Official Fix

REPORT CONFIDENCE

Confirmed

Temporal Score: 7.7

EPSS Score

0.01905

probability of exploitation in the next 30 days

0.77039 percentile - updated 2026-06-21

View on FIRST.org

Affected Products

13 affected products

Product	KB Article	Severity	Impact	Restart Required
Windows Server 2008 for 32-bit Systems Service Pack 2 5055609 (Monthly Rollup) 5055596 (Security Only) Important Elevation of Privilege 5053888 Base: 8.8 Temporal: 7.7 Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C 6.0.6003.23220 Yes None Windows Server 2008 for 32-bit Systems Service Pack 2 (Server Core installation) 5055609 (Monthly Rollup) 5055596 (Security Only) Important Elevation of Privilege 5053888 Base: 8.8 Temporal: 7.7 Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C 6.0.6003.23220 Yes None Windows Server 2008 for x64-based Systems Service Pack 2 5055609 (Monthly Rollup) 5055596 (Security Only) Important Elevation of Privilege 5053888 Base: 8.8 Temporal: 7.7 Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C 6.0.6003.23220 Yes None Windows Server 2008 for x64-based Systems Service Pack 2 (Server Core installation) 5055609 (Monthly Rollup) 5055596 (Security Only) Important Elevation of Privilege 5053888 Base: 8.8 Temporal: 7.7 Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C 6.0.6003.23220 Yes None Windows Server 2008 R2 for x64-based Systems Service Pack 1 5055561 (Monthly Rollup) 5055570 (Security Only) Important Elevation of Privilege 5053620 Base: 8.8 Temporal: 7.7 Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C 6.1.7601.27670 Yes None Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation) 5055561 (Monthly Rollup) 5055570 (Security Only) Important Elevation of Privilege 5053620 Base: 8.8 Temporal: 7.7 Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C 6.1.7601.27670 Yes None Windows Server 2012	`5055581 (Monthly Rollup)`	Important	Elevation of Privilege	Yes
Windows Server 2012 (Server Core installation)	`5055581 (Monthly Rollup)`	Important	Elevation of Privilege	Yes
Windows Server 2012 R2	`5055557 (Monthly Rollup)`	Important	Elevation of Privilege	Yes
Windows Server 2012 R2 (Server Core installation)	`5055557 (Monthly Rollup)`	Important	Elevation of Privilege	Yes
Windows Server 2016	`5055521 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server 2016 (Server Core installation)	`5055521 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server 2019	`5055519 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server 2019 (Server Core installation)	`5055519 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server 2022	`5055526 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server 2022 (Server Core installation)	`5055526 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server 2022, 23H2 Edition (Server Core installation)	`5055527 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server 2025	`5055523 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server 2025 (Server Core installation)	`5055523 (Security Update)`	Important	Elevation of Privilege	Yes

Patches

7 patches

Article	Type	Restart
`5055581`	Monthly Rollup	Yes
`5055557`	Monthly Rollup	Yes
`5055521`	Security Update	Yes
`5055519`	Security Update	Yes
`5055526`	Security Update	Yes
`5055527`	Security Update	Yes
`5055523`	Security Update	Yes

Known Exploits

No known exploits have been linked for this CVE yet. When available, exploit references will be sourced from public repositories and may be unverified, incomplete, or non-functional. Always review code carefully before use in any environment.

Acknowledgments

Oscar Virot

References

MSRC Advisory MITRE NVD