CVE-2026-27908 — Windows TDI Translation Driver (tdx.sys) Elevation of Privilege Vulnerability

Executive Summary

Use after free in Windows TDI Translation Driver (tdx.sys) allows an authorized attacker to elevate privileges locally.

Overview

7

CVSS HIGH

Important

MS Severity

Not Exploited

MS Exploit Status

More Likely

MS Exploit Likelihood

Category Elevation of Privilege

Weakness CWE-416: Use After Free

Released Apr 14 2026

Last Updated Apr 14 2026

Publicly Disclosed No

CISA KEV Not Listed

Known Exploits None Known

EPSS Score 0.01552 — 0.72908 percentile

NVD CVSS 7 HIGH — matches MSRC

CVSS Vector

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

ATTACK VECTOR

Local

ATTACK COMPLEXITY

High

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: 6.1

EPSS Score

0.01552

probability of exploitation in the next 30 days

0.72908 percentile - updated 2026-08-14

View on FIRST.org

Affected Products

31 affected products

Product	KB Article	Severity	Impact	Restart Required
Windows 10 Version 1607 for 32-bit Systems	`5082198 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 1607 for x64-based Systems	`5082198 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 1809 for 32-bit Systems	`5082123 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 1809 for x64-based Systems	`5082123 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 21H2 for 32-bit Systems	`5082200 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 21H2 for ARM64-based Systems	`5082200 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 21H2 for x64-based Systems	`5082200 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 22H2 for 32-bit Systems	`5082200 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 22H2 for ARM64-based Systems	`5082200 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 22H2 for x64-based Systems	`5082200 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 11 Version 23H2 for ARM64-based Systems	`5082052 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 11 Version 23H2 for x64-based Systems	`5082052 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 11 Version 24H2 for ARM64-based Systems	`5083769 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 11 Version 24H2 for x64-based Systems	`5083769 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 11 Version 25H2 for ARM64-based Systems	`5083769 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 11 Version 25H2 for x64-based Systems	`5083769 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 11 Version 26H1 for ARM64-based Systems	`5083768 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 11 version 26H1 for x64-based Systems	`5083768 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server 2012	`5082127 (Monthly Rollup)`	Important	Elevation of Privilege	Yes
Windows Server 2012 (Server Core installation)	`5082127 (Monthly Rollup)`	Important	Elevation of Privilege	Yes
Windows Server 2012 R2	`5082126 (Monthly Rollup)`	Important	Elevation of Privilege	Yes
Windows Server 2012 R2 (Server Core installation)	`5082126 (Monthly Rollup)`	Important	Elevation of Privilege	Yes
Windows Server 2016	`5082198 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server 2016 (Server Core installation)	`5082198 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server 2019	`5082123 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server 2019 (Server Core installation)	`5082123 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server 2022	`5082142 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server 2022 (Server Core installation)	`5082142 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server 2022, 23H2 Edition (Server Core installation)	`5082060 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server 2025	`5082063 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server 2025 (Server Core installation)	`5082063 (Security Update)`	Important	Elevation of Privilege	Yes

Patches

11 patches

Article	Type	Restart
`5082198`	Security Update	Yes
`5082123`	Security Update	Yes
`5082200`	Security Update	Yes
`5082052`	Security Update	Yes
`5083769`	Security Update	Yes
`5083768`	Security Update	Yes
`5082127`	Monthly Rollup	Yes
`5082126`	Monthly Rollup	Yes
`5082142`	Security Update	Yes
`5082060`	Security Update	Yes
`5082063`	Security Update	Yes

Patch Diff

ghidriff · tdx.sys (KB5083769)

Use-after-free (CWE-416) via a race in the Windows TDI Translation Driver tdx.sys TL endpoint/connection lifecycle, local EoP to SYSTEM (AC:H race). tdx.sys translates legacy TDI calls to TCP/IP; it tracks transport-address / TL-endpoint / connection objects that request paths (TdxIssueListenRequest, TdxIssueQueryAddressRequest, TdxIssueIoControlRequest) use while teardown paths (TdxDeactivateTransportAddress, TdxShutdownEndpointConnection, TdxCleanupObjectHeader) free them. PRE: request paths used the endpoint/connection object without holding a reference under the endpoint lock, so a concurrent deactivate/shutdown could free the object while a request was still using it - a race yielding a use-after-free of the TL endpoint/connection. Because tdx runs in the kernel and the TDI request interface is reachable by a local user, winning the race (AC:H) is a local EoP-to-SYSTEM primitive. Diff of tdx.sys 10.0.26100.7920 -> .8246 (Apr 14 2026, KB5083769) confirms the fix: gated behind CFR flags Feature_490931514 (request paths) and Feature_2411928891 (deactivate), the request handlers now take an explicit reference on the object under the endpoint spinlock before use - TdxIncrementTlEndpointReference / DbgTdxReferenceConnection / DbgTdxReferenceTransportAddress acquired under KeAcquireSpinLockRaiseToDpc(endpoint+2) - and teardown decrements under the same lock (TdxDecrementTlEndpointReference), so the object cannot be freed while a request holds it, closing the race/UAF.

Pre-patch version 10.0.26100.7920 Download

Post-patch version 10.0.26100.8246 Download

Function	Address	Change	Note
`TdxIssueQueryAddressRequest`	`code change`	code (reference taken under endpoint lock before use, CFR-gated)	Post (Feature_490931514): under KeAcquireSpinLock(endpoint+2), calls TdxIncrementTlEndpointReference + DbgTdxReferenceConnection before using the connection/endpoint, then releases; prevents concurrent free.
`TdxIssueListenRequest`	`code change`	code (transport-address referenced under lock, CFR-gated)	Post (Feature_490931514): DbgTdxReferenceTransportAddress + KeAcquireSpinLockRaiseToDpc around the request issuance.
`TdxDeactivateTransportAddress`	`code change`	code (teardown decrements under lock, CFR-gated)	Post (Feature_2411928891): takes the endpoint spinlock and TdxDecrementTlEndpointReference during deactivation so teardown is serialized against in-flight requests.
`DbgTdxReferenceConnection / DbgTdxDereferenceConnection / TdxDecrementTlEndpointReference / TdxCleanupObjectHeader / TdxShutdownEndpointConnection`	`code change`	code (reference lifecycle reworked)	Connection/endpoint reference and cleanup paths updated to the take-reference-under-lock discipline.
`Feature_490931514 / Feature_2411928891`	`gate`	added (CFR gate)	CFR flags gating the reference-under-lock request paths and the serialized teardown; the original unsynchronized paths still ship when disabled.

View full diff report View RCA report

Attack Path

A TDI request uses a TL endpoint/connection object that a concurrent teardown frees, causing a UAF

Derived from the patch delta: the checks added by the vendor identify which fields crossed a trust boundary unvalidated. Reachability and privilege are taken from the call chain in the RCA report.

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

Angelboy (@scwuaptx)

References

MSRC Advisory MITRE NVD