CVE-2026-62889: Windows Secure Socket Tunneling Protocol (SSTP) Remote Code Execution Vulnerability

highCVSS 8.1CVE-2026-62889

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

CSIRTS triage

vendor: Microsoft product: Windows Secure Socket Tunneling Protocol (SSTP)Remote code execution Memory corruption

What: A double free vulnerability in Windows SSTP allows remote code execution over a network.
Who is affected: Systems running Windows SSTP server or client components that receive untrusted network traffic.
Urgency: High severity (CVSS 8.1); not currently exploited but remotely exploitable without authentication.
Action: Apply Windows security updates that address CVE-2026-62889 when available.

AI-assisted analysis generated from the source advisory — verify against the original.

⚡ Watch Windows Secure Socket Tunneling Protocol (SSTP)

Get an email when a new Windows Secure Socket Tunneling Protocol (SSTP) advisory drops — max one per day, one-click unsubscribe.

Details

Source: Microsoft Security Response Center (INTL · vendor-psirt · site)
Severity: high — CVSS 8.1
Published: 2026-08-11
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-62889

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-628890.56% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 44% of all EPSS-scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-62889	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

critical[NEW] [critical] Microsoft Windows Products: Multiple vulnerabilitiescert-bund
unknownexploitedNCSC-2026-0284 [1.00] [M/H] Vulnerabilities patched in Microsoft Windowsncsc-nl
highCVE-2026-62889: Double free in Windows Secure Socket Tunneling Protocol (SSTP) allows an unauthorized attacker…nvd

Recent advisories for Windows Secure Socket

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

highCVE-2026-62889: Double free in Windows Secure Socket Tunneling Protocol (SSTP) allows an unauthorized attacker…nvd · 2026-08-11
highCVE-2026-50694: Use after free in Windows Secure Socket Tunneling Protocol (SSTP) allows an unauthorized attac…nvd · 2026-07-14
highCVE-2026-50694: Windows Secure Socket Tunneling Protocol (SSTP) Remote Code Execution Vulnerabilitymsrc · 2026-07-14