CVE-2017-12176: Debian Linux

Critical severity, CVSS 9.8. EPSS: 4.2% chance of exploitation in the next 30 days.

xorg-x11-server before 1.19.5 was missing extra length validation in ProcEstablishConnection function allowing malicious X client to cause X server to crash or possibly execute arbitrary code.

Affected products

• Debian Debian Linux: version 8.0 only; version 9.0 only
• X.org X Server: before 1.19.5 (fixed in 1.19.5)

Published 2018-01-24. Last modified 2026-06-17.