RHSA-2020:3875 - Security Advisory

Topic

An update for tigervnc is now available for Red Hat Enterprise Linux 7.

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

Virtual Network Computing (VNC) is a remote display system which allows users to view a computing desktop environment not only on the machine where it is running, but from anywhere on the Internet and from a wide variety of machine architectures. TigerVNC is a suite of VNC servers and clients.

Security Fix(es):

• tigervnc: Stack use-after-return due to incorrect usage of stack memory in ZRLEDecoder (CVE-2019-15691)
• tigervnc: Heap buffer overflow triggered from CopyRectDecoder due to incorrect value checks (CVE-2019-15692)
• tigervnc: Heap buffer overflow in TightDecoder::FilterGradient (CVE-2019-15693)
• tigervnc: Heap buffer overflow in DecodeManager::decodeRect (CVE-2019-15694)
• tigervnc: Stack buffer overflow in CMsgReader::readSetCursor (CVE-2019-15695)

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 7.9 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 Server 7 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 7 x86_64
• Red Hat Enterprise Linux Workstation 7 x86_64
• Red Hat Enterprise Linux Desktop 7 x86_64
• Red Hat Enterprise Linux for IBM z Systems 7 s390x
• Red Hat Enterprise Linux for Power, big endian 7 ppc64
• Red Hat Enterprise Linux for Scientific Computing 7 x86_64
• Red Hat Enterprise Linux for Power, little endian 7 ppc64le
• Red Hat Enterprise Linux Server - Extended Life Cycle Support (for IBM z Systems) 7 s390x
• Red Hat Enterprise Linux Server - Extended Life Cycle Support for IBM Power, big endian 7 ppc64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support for IBM Power, little endian 7 ppc64le

Fixes

• BZ - 1789527 - CVE-2019-15692 tigervnc: Heap buffer overflow triggered from CopyRectDecoder due to incorrect value checks
• BZ - 1789908 - CVE-2019-15691 tigervnc: Stack use-after-return due to incorrect usage of stack memory in ZRLEDecoder
• BZ - 1790313 - CVE-2019-15693 tigervnc: Heap buffer overflow in TightDecoder::FilterGradient
• BZ - 1790315 - CVE-2019-15694 tigervnc: Heap buffer overflow in DecodeManager::decodeRect
• BZ - 1790318 - CVE-2019-15695 tigervnc: Stack buffer overflow in CMsgReader::readSetCursor
• BZ - 1791996 - TigerVNC should not arbitrarily start on unspecified ports
• BZ - 1826822 - TigerVNC exits at startup

CVEs

• CVE-2019-15691
• CVE-2019-15692
• CVE-2019-15693
• CVE-2019-15694
• CVE-2019-15695

References

• https://access.redhat.com/security/updates/classification/#moderate
• https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/7.9_release_notes/index