RHSA-2021:1811 — Security Advisory

Red Hat Security Advisory: libvncserver security update

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Severity

Moderate

Red Hat Product Security

RHEL 8

Products

Official CSAF product identity

Published · May 18, 2021

Updated · June 27, 2026

Topic

An update for libvncserver is now available for Red Hat Enterprise Linux 8.

Red Hat Product Security has rated this update as having a security impact of Moderate. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.

Description

LibVNCServer is a C library that enables you to implement VNC server functionality into own programs.

Security Fix(es):

  • libvncserver: uninitialized memory contents are vulnerable to Information Leak (CVE-2018-21247)

  • libvncserver: buffer overflow in ConnectClientToUnixSock() (CVE-2019-20839)

  • libvncserver: libvncserver/rfbregion.c has a NULL pointer dereference (CVE-2020-14397)

  • libvncserver: libvncclient/rfbproto.c does not limit TextChat size (CVE-2020-14405)

  • libvncserver: libvncserver/rfbserver.c has a divide by zero which could result in DoS (CVE-2020-25708)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Additional Changes:

For detailed information on changes in this release, see the Red Hat Enterprise Linux 8.4 Release Notes linked from the References section.

Related CVEs

RHSA-2021:1811 — Red Hat Security Advisory: libvncserver security update | PulseLinux