EUVD-2026-44034
GHSA-4r8r-cjr4-hvqr
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
Local, authenticated foothold required (AV:L, PR:L) with low complexity and no UI; a missing crypto step enables data tampering and disclosure (I:H, C:H) with no availability effect.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
2DescriptionCVE.org
Missing cryptographic step in Windows CryptoAPI allows an authorized attacker to perform tampering locally.
AnalysisAI
Local tampering in Windows CryptoAPI (Crypt32) on Windows 11 (24H2/25H2/26H1) and Windows Server 2022/2025 stems from a missing cryptographic step, letting an authenticated local attacker undermine the integrity and confidentiality of cryptographically protected data. Microsoft rates it 7.1 (High) with high confidentiality and integrity impact; there is no public exploit identified at time of analysis and it is not on the CISA KEV list. A vendor patch is available through the MSRC update guide.
Technical ContextAI
Windows CryptoAPI (the crypt32.dll / cryptographic services stack) is the core OS component that applications rely on for certificate validation, signature verification, encryption, and key handling. The root cause is CWE-325 (Missing Required Cryptographic Step): a required operation in a cryptographic routine is omitted, weakening the guarantees the algorithm is supposed to provide. When a step such as a validation, padding check, integrity/MAC verification, or nonce/parameter handling is skipped, protected data can be forged or altered without detection, which is why Microsoft characterizes the impact as tampering. The CPE data scopes the flaw to Microsoft Windows 11 versions 24H2, 25H2 and 26H1, plus Windows Server 2022 and Windows Server 2025 (including the Server Core installation).
RemediationAI
Patch available per vendor advisory - apply the Microsoft security update for CVE-2026-55144 delivered through the monthly Windows cumulative update for your specific SKU, tracked at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55144; the exact fixed build/KB is not provided in the input data and should be taken from that advisory. Because exploitation requires authenticated local access, compensating controls until patching completes include restricting and monitoring interactive and remote-interactive logon rights to trusted administrators, enforcing least privilege to reduce the pool of low-privileged accounts that satisfy PR:L, and prioritizing patch deployment on multi-user and shared servers (Server 2022/2025, Server Core) where more principals can reach the local attack surface. No component-disable workaround is documented for CryptoAPI, and disabling cryptographic services is not viable as it would break certificate and signature validation across the OS, so patching is the only reliable fix.
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Same weakness CWE-325 – Missing Cryptographic Step
View allSame technique Information Disclosure
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External POC / Exploit Code
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