CVE-2015-1637: Microsoft Windows 7

Medium severity, CVSS 4.3. EPSS: 13.2% chance of exploitation in the next 30 days.

Schannel (aka Secure Channel) in Microsoft Windows Server 2003 SP2, Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8, Windows 8.1, Windows Server 2012 Gold and R2, and Windows RT Gold and 8.1 does not properly restrict TLS state transitions, which makes it easier for remote attackers to conduct cipher-downgrade attacks to EXPORT_RSA ciphers via crafted TLS traffic, related to the "FREAK" issue, a different vulnerability than CVE-2015-0204 and CVE-2015-1067.

Affected products

• Microsoft Windows 7: affected versions not specified
• Microsoft Windows 8: affected versions not specified
• Microsoft Windows 8.1: affected versions not specified
• Microsoft Windows Rt: affected versions not specified
• Microsoft Windows Rt 8.1: affected versions not specified
• Microsoft Windows Server 2003: affected versions not specified
• Microsoft Windows Server 2008: affected versions not specified; version r2 only
• Microsoft Windows Server 2012: affected versions not specified; version r2 only
• Microsoft Windows Vista: affected versions not specified

Published 2015-03-06. Last modified 2026-06-17.