Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Network-reachable unauthenticated SSTP service with full impact, but reliable use-after-free RCE needs heap grooming (SSVC Automatable:no), so AC:H rather than AC:L.
Primary rating from Vendor (microsoft).
CVSS VectorNVD
Lifecycle Timeline
6DescriptionNVD
Use after free in Windows Secure Socket Tunneling Protocol (SSTP) allows an unauthorized attacker to execute code over a network.
AnalysisAI
Remote code execution in Microsoft Windows Secure Socket Tunneling Protocol (SSTP) allows an unauthorized network attacker to run arbitrary code by triggering a use-after-free (CWE-416) memory-corruption condition. The flaw affects a broad range of Windows client and server releases from Windows 10 1607 and Server 2012 through Windows 11 26H1 and Server 2025, and per its CVSS 9.8 vector requires no authentication or user interaction. There is no public exploit identified at time of analysis, and the EPSS probability is modest (0.61%), so despite the critical score exploitation is not yet observed.
Technical ContextAI
SSTP is a Microsoft VPN tunneling protocol that carries PPP traffic inside an SSL/TLS 3.0 channel over TCP 443, implemented in the Windows RRAS/SSTP service stack. The root cause is CWE-416, a use-after-free: the SSTP code path frees a heap object but retains and later dereferences the stale pointer, letting an attacker who controls the freed/reallocated memory corrupt heap state and steer execution. The affected component ships as part of the Windows OS across the CPE-listed builds (Windows 10 1607/1809/21H2/22H2, Windows 11 24H2/25H2/26H1, and Windows Server 2012 through 2025, including Server Core installations), so any host exposing or processing SSTP traffic is potentially in scope.
RemediationAI
Patch available per vendor advisory: apply the Microsoft security update for CVE-2026-50694, upgrading to at least the fixed build for your edition (e.g., Windows 11 24H2 10.0.26100.8875, Windows 11 25H2 10.0.26200.8875, Windows 11 26H1 10.0.28000.2269, Windows Server 2022 10.0.20348.5386, Windows Server 2025 10.0.26100.33158, Server 2012 R2 6.3.9600.23291, Server 2012 6.2.9200.26226, and Windows 10 22H2 10.0.19045.7548), as listed at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50694. Where patching must be deferred, the highest-value compensating control is to disable the SSTP VPN feature/RRAS SSTP role if not in use, or block/restrict inbound TCP 443 SSTP traffic to the RRAS endpoint at the network edge and permit it only from trusted VPN clients - trade-off: this breaks legitimate SSTP VPN connectivity for remote users, so organizations relying on SSTP should prioritize the patch and use TLS-terminating gateways or IP allow-lists as interim protection rather than a permanent fix.
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Same weakness CWE-416 – Use After Free
View allSame technique Use After Free
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External POC / Exploit Code
Leaving vuln.today
EUVD-2026-44046
GHSA-x25h-v5pq-j424