CVE-2026-50694 — Windows Secure Socket Tunneling Protocol (SSTP) Remote Code Execution Vulnerability

Executive Summary

Use after free in Windows Secure Socket Tunneling Protocol (SSTP) allows an unauthorized attacker to execute code over a network.

Overview

9.8

CVSS CRITICAL

Critical

MS Severity

Not Exploited

MS Exploit Status

Exploitation Unlikely

MS Exploit Likelihood

Category Remote Code Execution

Weakness CWE-416: Use After Free

Released Jul 14 2026

Last Updated Jul 14 2026

Publicly Disclosed No

CISA KEV Not Listed

Known Exploits None Known

EPSS Score 0.00662 — 0.48571 percentile

NVD CVSS 9.8 CRITICAL — differs from MSRC

CVSS Vector

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

ATTACK VECTOR

Network

ATTACK COMPLEXITY

Low

PRIVILEGES REQUIRED

None

USER INTERACTION

None

SCOPE

Unchanged

CONFIDENTIALITY

High

INTEGRITY

High

AVAILABILITY

High

EXPLOIT CODE MATURITY

Unproven

REMEDIATION LEVEL

Official Fix

REPORT CONFIDENCE

Confirmed

Temporal Score: 7.1

EPSS Score

0.00662

probability of exploitation in the next 30 days

0.48571 percentile - updated 2026-08-14

View on FIRST.org

Affected Products

27 affected products

Product	KB Article	Severity	Impact	Restart Required
Windows 10 Version 1607 for 32-bit Systems	`5099535 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 1607 for x64-based Systems	`5099535 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 1809 for 32-bit Systems	`5099538 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 1809 for x64-based Systems	`5099538 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 21H2 for 32-bit Systems	`5099539 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 21H2 for ARM64-based Systems	`5099539 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 21H2 for x64-based Systems	`5099539 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 22H2 for 32-bit Systems	`5099539 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 22H2 for ARM64-based Systems	`5099539 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 22H2 for x64-based Systems	`5099539 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 11 Version 24H2 for ARM64-based Systems	`5101650 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 11 Version 24H2 for x64-based Systems	`5101650 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 11 Version 25H2 for ARM64-based Systems	`5101650 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 11 Version 25H2 for x64-based Systems	`5101650 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 11 Version 26H1 for ARM64-based Systems	`5101649 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 11 version 26H1 for x64-based Systems	`5095051 (Security Update)`	Critical	Remote Code Execution	Yes
Windows Server 2012	`5099445 (Monthly Rollup)`	Critical	Remote Code Execution	Yes
Windows Server 2012 (Server Core installation)	`5099445 (Monthly Rollup)`	Critical	Remote Code Execution	Yes
Windows Server 2012 R2	`5099444 (Monthly Rollup)`	Critical	Remote Code Execution	Yes
Windows Server 2012 R2 (Server Core installation)	`5099444 (Monthly Rollup)`	Critical	Remote Code Execution	Yes
Windows Server 2016	`5099535 (Security Update)`	Critical	Remote Code Execution	Yes
Windows Server 2016 (Server Core installation)	`5099535 (Security Update)`	Critical	Remote Code Execution	Yes
Windows Server 2019	`5099538 (Security Update)`	Critical	Remote Code Execution	Yes
Windows Server 2019 (Server Core installation)	`5099538 (Security Update)`	Critical	Remote Code Execution	Yes
Windows Server 2022	`5099540 (Security Update)`	Critical	Remote Code Execution	Yes
Windows Server 2025	`5099536 (Security Update)`	Critical	Remote Code Execution	Yes
Windows Server 2025 (Server Core installation)	`5099536 (Security Update)`	Critical	Remote Code Execution	Yes

Patches

10 patches

Article	Type	Restart
`5099535`	Security Update	Yes
`5099538`	Security Update	Yes
`5099539`	Security Update	Yes
`5101650`	Security Update	Yes
`5101649`	Security Update	Yes
`5095051`	Security Update	Yes
`5099445`	Monthly Rollup	Yes
`5099444`	Monthly Rollup	Yes
`5099540`	Security Update	Yes
`5099536`	Security Update	Yes

Patch Diff

ghidriff · sstpsvc.dll (KB5101650)

Use-after-free (CWE-416) via an unsynchronized handle lookup in the Windows SSTP service sstpsvc.dll, Critical pre-auth network RCE. The service resolves a client-supplied 32-bit handle to a connection object through the handle table (SstpSvcGlobals index 22). PRE: HfGetPointerFromHandle32 was called WITHOUT holding the handle-table lock, and the object's lifetime reference was acquired outside that lock; only the object's own critical section (obj+288) was entered afterward. A concurrent handle removal (which takes the table lock) could remove the handle and drop the last reference, freeing the object, in the window between the lockless lookup and its use -> UAF. Diff of sstpsvc.dll 10.0.26100.8737 -> .8875 (Jul 14 2026, KB5101650) confirms the fix: gated behind CFR flag Feature_1207409977, the lookup AND the reference increment (obj+0xD0) are moved inside the handle-table critical section (SstpSvcGlobals+0xB8 / +184), synchronizing with concurrent handle removal that needs the same lock; release paths DereferenceRefCount(obj+0xD0). The object's own critical section is still acquired at the same later point. Note: our diff shows Feature_1207409977 (build/arch); the lookup+AddRef-under-table-lock is as described. AV:N/AC:H/PR:N.

Pre-patch version 10.0.26100.8737 Download

Post-patch version 10.0.26100.8875 Download

Function	Address	Change	Note
`HfGetPointerFromHandle32 caller (SSTP handle-resolve path)`	`code change`	code (lookup+AddRef moved under table lock, CFR-gated)	Pre: HfGetPointerFromHandle32(table, handle, &obj) with no table lock; ref taken outside the lock; only obj+288 critical section entered later. Post (Feature_1207409977): EnterCriticalSection(SstpSvcGlobals+0xB8); lookup; if found, obj+0xD0 refcount++ ; LeaveCriticalSection - so lookup+AddRef are atomic vs concurrent handle removal.
`Feature_1207409977`	`gate`	added (CFR gate)	CFR flag gating the table-lock-synchronized lookup/AddRef; original lockless path still ships when disabled.

View full diff report View RCA report

Attack Path

SSTP resolves a client handle to an object without the table lock, so a concurrent handle removal frees it mid-use

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.

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

Microsoft has not published researcher acknowledgments for this CVE, or they are not yet reflected in our data source. Check the MSRC advisory directly for the most current credit information.

References

MSRC Advisory MITRE NVD