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CVE-2018-20019: LibVNC: Remote code execution

CVE-2018-20019 is rated critical with a CVSS v3.1 base score of 9.8 and NVD lists 9 affected products, including Libvnc Project Libvncserver. Per its scoring, it can be exploited over the network, without authentication, without any user interaction. The scored impact on confidentiality, integrity and availability is the highest available.

Vulnerability description

LibVNC before commit a83439b9fbe0f03c48eb94ed05729cb016f8b72f contains multiple heap out-of-bound write vulnerabilities in VNC client code that can result remote code execution

Severity breakdown

CVSS v3.1 9.8: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack vector: Network. Exploitable remotely over the network, with no need for local or physical access.
Attack complexity: Low. No special conditions; the attack can be repeated reliably.
Privileges required: None. No account or prior access is needed.
User interaction: None. No action from any user is needed.
Scope: Unchanged. Impact stays within the vulnerable component.
Confidentiality impact: High. Total loss of confidentiality; sensitive data can be fully disclosed.
Integrity impact: High. Total loss of integrity; data or system state can be fully modified.
Availability impact: High. Total loss of availability; the component can be shut down.

Underlying weakness

CWE-787: Out-of-bounds Write

The product writes data past the end, or before the beginning, of the intended buffer.

Affected products

Libvnc Project Libvncserver: before 0.9.12
Canonical Ubuntu Linux: 14.04; 16.04; 18.04; 18.10
Debian Linux: 8.0; 9.0
Siemens Simatic Itc1500 Firmware: from 3.0.0.0 before 3.2.1.0
Siemens Simatic Itc1500 Pro Firmware: from 3.0.0.0 before 3.2.1.0
Siemens Simatic Itc1900 Firmware: from 3.0.0.0 before 3.2.1.0
Siemens Simatic Itc1900 Pro Firmware: from 3.0.0.0 before 3.2.1.0
Siemens Simatic Itc2200 Firmware: from 3.0.0.0 before 3.2.1.0
Siemens Simatic Itc2200 Pro Firmware: from 3.0.0.0 before 3.2.1.0