RHSA-2021:1811 - Security Advisory

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.

Solution

For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

Affected Products

• Red Hat Enterprise Linux for x86_64 8 x86_64
• Red Hat Enterprise Linux for IBM z Systems 8 s390x
• Red Hat Enterprise Linux for Power, little endian 8 ppc64le
• Red Hat Enterprise Linux for ARM 64 8 aarch64
• Red Hat CodeReady Linux Builder for x86_64 8 x86_64
• Red Hat CodeReady Linux Builder for Power, little endian 8 ppc64le
• Red Hat CodeReady Linux Builder for ARM 64 8 aarch64
• Red Hat CodeReady Linux Builder for IBM z Systems 8 s390x

Fixes

• BZ - 1849877 - CVE-2019-20839 libvncserver: buffer overflow in ConnectClientToUnixSock()
• BZ - 1849886 - CVE-2018-21247 libvncserver: uninitialized memory contents are vulnerable to Information Leak
• BZ - 1860325 - CVE-2020-14405 libvncserver: libvncclient/rfbproto.c does not limit TextChat size
• BZ - 1860344 - CVE-2020-14397 libvncserver: libvncserver/rfbregion.c has a NULL pointer dereference
• BZ - 1896739 - CVE-2020-25708 libvncserver: libvncserver/rfbserver.c has a divide by zero which could result in DoS

CVEs

• CVE-2018-21247
• CVE-2019-20839
• CVE-2020-14397
• CVE-2020-14405
• CVE-2020-25708

References

• https://access.redhat.com/security/updates/classification/#moderate
• https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html/8.4_release_notes/