CVE-2026-55144 — Windows Cryptography API: Next Generation (CNG) Tampering Vulnerability

Executive Summary

Missing cryptographic step in Windows CryptoAPI allows an authorized attacker to perform tampering locally.

Overview

7.1

CVSS HIGH

Important

MS Severity

Not Exploited

MS Exploit Status

Exploitation Unlikely

MS Exploit Likelihood

Category Tampering

Weakness CWE-325: Missing Cryptographic Step

Released Jul 14 2026

Last Updated Jul 14 2026

Publicly Disclosed No

CISA KEV Not Listed

Known Exploits None Known

EPSS Score 0.00164 — 0.06103 percentile

NVD CVSS 7.1 HIGH — matches MSRC

CVSS Vector

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

ATTACK VECTOR

Local

ATTACK COMPLEXITY

Low

PRIVILEGES REQUIRED

Low

USER INTERACTION

None

SCOPE

Unchanged

CONFIDENTIALITY

High

INTEGRITY

High

AVAILABILITY

None

EXPLOIT CODE MATURITY

Unproven

REMEDIATION LEVEL

Official Fix

REPORT CONFIDENCE

Confirmed

Temporal Score: 6.2

EPSS Score

0.00164

probability of exploitation in the next 30 days

0.06103 percentile - updated 2026-08-14

View on FIRST.org

Affected Products

9 affected products

Product	KB Article	Severity	Impact	Restart Required
Windows 11 Version 24H2 for ARM64-based Systems	`5101650 (Security Update)`	Important	Tampering	Yes
Windows 11 Version 24H2 for x64-based Systems	`5101650 (Security Update)`	Important	Tampering	Yes
Windows 11 Version 25H2 for ARM64-based Systems	`5101650 (Security Update)`	Important	Tampering	Yes
Windows 11 Version 25H2 for x64-based Systems	`5101650 (Security Update)`	Important	Tampering	Yes
Windows 11 Version 26H1 for ARM64-based Systems	`5101649 (Security Update)`	Important	Tampering	Yes
Windows 11 version 26H1 for x64-based Systems	`5101649 (Security Update)`	Important	Tampering	Yes
Windows Server 2022	`5099540 (Security Update)`	Important	Tampering	Yes
Windows Server 2025	`5099536 (Security Update)`	Important	Tampering	Yes
Windows Server 2025 (Server Core installation)	`5099536 (Security Update)`	Important	Tampering	Yes

Patches

4 patches

Article	Type	Restart
`5101650`	Security Update	Yes
`5101649`	Security Update	Yes
`5099540`	Security Update	Yes
`5099536`	Security Update	Yes

Exploits & PoC

No public exploit or PoC has been linked for this CVE yet. When available, references are sourced from public repositories and may be unverified or non-functional — review carefully before use.

Detection Rules

No public Sigma or Nuclei detection rule has been mapped to this CVE yet. Coverage is concentrated on exploited / high-profile vulnerabilities; check SigmaHQ for updates.

Acknowledgments

Samuel Lee with Microsoft

References

MSRC Advisory MITRE NVD