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CVE-2018-14599: X.Org Libx11: Off-by-one Error

CVE-2018-14599 is rated critical with a CVSS v3.1 base score of 9.8 and affects X.Org Libx11, along with 6 other products in NVD’s configuration data. 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

An issue was discovered in libX11 through 1.6.5. The function XListExtensions in ListExt.c is vulnerable to an off-by-one error caused by malicious server responses, leading to DoS or possibly unspecified other impact.

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-193: Off-by-one Error

A product calculates or uses an incorrect maximum or minimum value that is 1 more, or 1 less, than the correct value.

Affected products

X.Org Libx11: up to and including 1.6.5
Canonical Ubuntu Linux: 12.04; 14.04; 16.04; 18.04
Debian Linux: 8.0
Fedoraproject: 28
Red Hat Enterprise Linux Desktop: 7.0
Red Hat Enterprise Linux Server: 7.0
Red Hat Enterprise Linux Workstation: 7.0