A tightvnc security update has been released for Debian GNU/Linux 8 LTS

Package : tightvnc
Version : 1.3.9-6.5+deb8u1
CVE ID : CVE-2014-6053 CVE-2018-7225 CVE-2019-8287 CVE-2018-20021
CVE-2018-20022 CVE-2019-15678 CVE-2019-15679 CVE-2019-15680
CVE-2019-15681
Debian Bug : 945364

Several vulnerabilities have recently been discovered in TightVNC 1.x, an
X11 based VNC server/viewer application for Windows and Unix.

CVE-2014-6053

The rfbProcessClientNormalMessage function in rfbserver.c in TightVNC
server did not properly handle attempts to send a large amount of
ClientCutText data, which allowed remote attackers to cause a denial
of service (memory consumption or daemon crash) via a crafted message
that was processed by using a single unchecked malloc.

CVE-2018-7225

rfbProcessClientNormalMessage() in rfbserver.c did not sanitize
msg.cct.length, leading to access to uninitialized and potentially
sensitive data or possibly unspecified other impact (e.g., an integer
overflow) via specially crafted VNC packets.

CVE-2019-8287

TightVNC code contained global buffer overflow in HandleCoRREBBP
macro function, which could potentially have result in code
execution. This attack appeared to be exploitable via network
connectivity.

(aka CVE-2018-20020/libvncserver)

CVE-2018-20021

TightVNC in vncviewer/rfbproto.c contained a CWE-835: Infinite loop
vulnerability. The vulnerability allowed an attacker to consume
an excessive amount of resources like CPU and RAM.

CVE-2018-20022

TightVNC's vncviewer contained multiple weaknesses CWE-665: Improper
Initialization vulnerability in VNC client code that allowed
attackers to read stack memory and could be abused for information
disclosure. Combined with another vulnerability, it could be used to
leak stack memory layout and in bypassing ASLR.

CVE-2019-15678

TightVNC code version contained heap buffer overflow in
rfbServerCutText handler, which could have potentially resulted in
code execution. This attack appeared to be exploitable via network
connectivity.

(partially aka CVE-2018-20748/libvnvserver)

CVE-2019-15679

TightVNC's vncviewer code contained a heap buffer overflow in
InitialiseRFBConnection function, which could have potentially
resulted in code execution. This attack appeared to be exploitable
via network connectivity.

(partially aka CVE-2018-20748/libvnvserver)

CVE-2019-15680

TightVNC's vncviewer code contained a null pointer dereference in
HandleZlibBPP function, which could have resulted in Denial of System
(DoS). This attack appeared to be exploitable via network
connectivity.

CVE-2019-15681

TightVNC contained a memory leak (CWE-655) in VNC server code, which
allowed an attacker to read stack memory and could have been abused
for information disclosure. Combined with another vulnerability, it
could have been used to leak stack memory and bypass ASLR. This
attack appeared to be exploitable via network connectivity.

For Debian 8 "Jessie", these problems have been fixed in version
1.3.9-6.5+deb8u1.

We recommend that you upgrade your tightvnc packages.

Further information about Debian LTS security advisories, how to apply
these updates to your system and frequently asked questions can be
found at: https://wiki.debian.org/LTS