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HIGH

libX11: Crash on invalid reply in XListExtensions in ListExt.c

Published Aug 24, 2018

Description

An issue was discovered in XListExtensions in ListExt.c in libX11 through 1.6.5. A malicious server can send a reply in which the first string overflows, causing a variable to be set to NULL that will be freed later on, leading to DoS (segmentation fault).

Affected products

Remediation

Red Hat statement

This issue did not affect the versions of libX11 as shipped with Red Hat Enterprise Linux 5 as they did not include the vulnerable code. To exploit the vulnerability an attacker would need to have already compromised the X server used by your applications. Normally, the X client that runs libX11 and the X server runs on the same machine, thus if an attacker can trigger this flaw he has already compromised the X server, which runs as root, and he has already full control on the system. If the X client runs on another system than the X server (e.g. DISPLAY environment variable is used and it points to an X server on another system) then exploiting this vulnerability would only crash the client, which should not be run with high privileges. For the above reasons, this flaw was rated as Moderate Impact.

References (17)

Change history (0)

No recorded changes yet.

Sources
CVE.org / MITRE
Status PUBLISHED
Assigner mitre
Published Aug 24, 2018
Updated Aug 5, 2024
Reserved Jul 26, 2018
NVD
Status Modified
Modified Jun 17, 2026
Red Hat
Severity Moderate
Public date Aug 21, 2018
ENISA EUVD
Assigner mitre
Published Aug 24, 2018
Updated Aug 5, 2024
Exploited since n/a
EUVD-2018-6505