RHSA-2021:1811 — Security Advisory
Red Hat Security Advisory: libvncserver security update
Severity
ModerateRed Hat Product Security
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)
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libvncserver: buffer overflow in ConnectClientToUnixSock() (CVE-2019-20839)
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libvncserver: libvncserver/rfbregion.c has a NULL pointer dereference (CVE-2020-14397)
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libvncserver: libvncclient/rfbproto.c does not limit TextChat size (CVE-2020-14405)
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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.