CVE-2015-3963: Windriver Vxworks

Medium severity, CVSS 5.8. EPSS: 3.7% chance of exploitation in the next 30 days.

Wind River VxWorks before 5.5.1, 6.5.x through 6.7.x before 6.7.1.1, 6.8.x before 6.8.3, 6.9.x before 6.9.4.4, and 7.x before 7 ipnet_coreip 1.2.2.0, as used on Schneider Electric SAGE RTU devices before J2 and other devices, does not properly generate TCP initial sequence number (ISN) values, which makes it easier for remote attackers to spoof TCP sessions by predicting an ISN value.

Affected products

• Windriver Vxworks: from 6.5, up to and including 6.6; from 6.7, before 6.7.1.1 (fixed in 6.7.1.1); from 6.8, before 6.8.3 (fixed in 6.8.3); from 6.9, before 6.9.4.4 (fixed in 6.9.4.4); version 6.6.3 only; version 6.6.4 only; …

Published 2015-08-04. Last modified 2026-06-17.