CVE-2018-21247: Canonical Ubuntu Linux

High severity, CVSS 7.5. EPSS: 2.5% chance of exploitation in the next 30 days.

An issue was discovered in LibVNCServer before 0.9.13. There is an information leak (of uninitialized memory contents) in the libvncclient/rfbproto.c ConnectToRFBRepeater function.

Affected products

• Canonical Ubuntu Linux: version 14.04 only; version 16.04 only; version 18.04 only; version 18.10 only
• Debian Debian Linux: version 8.0 only; version 9.0 only
• Libvnc Project Libvncserver: up to and including 0.9.12
• Opensuse Leap: version 15.2 only
• Siemens SIMATIC ITC1500 Firmware: from 3.0.0.0, before 3.2.1.0 (fixed in 3.2.1.0)
• Siemens SIMATIC ITC1500 Pro Firmware: from 3.0.0.0, before 3.2.1.0 (fixed in 3.2.1.0)
• Siemens SIMATIC ITC1900 Firmware: from 3.0.0.0, before 3.2.1.0 (fixed in 3.2.1.0)
• Siemens SIMATIC ITC1900 Pro Firmware: from 3.0.0.0, before 3.2.1.0 (fixed in 3.2.1.0)
• Siemens SIMATIC ITC2200 Firmware: from 3.0.0.0, before 3.2.1.0 (fixed in 3.2.1.0)
• Siemens SIMATIC ITC2200 Pro Firmware: from 3.0.0.0, before 3.2.1.0 (fixed in 3.2.1.0)

Published 2020-06-17. Last modified 2026-06-17.