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.

NOTE: Tenable Network Security has extracted the preceding description block directly from the DLA security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

Detections

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Debian DLA-2045-1 : tightvnc security update

critical Nessus Plugin ID 132345

Version 1.6

Version 1.5

Version 1.6 Apr 2, 2024, 2:43 PM CVSS temporal metrics ("CVSSv2 temporal vector" set to "CVSS2#E:POC/RL:OF/RC:C". "CVSSv3 temporal vector" set to "CVSS:3.0/E:P/RL:O/RC:C") Plugin Feed: 202404021443
Version 1.5 Apr 2, 2024, 12:34 PM CVSS temporal metrics ("CVSSv2 temporal vector" set to "CVSS2#E:POC/RL:OF/RC:C") CVSS temporal metrics ("CVSSv3 temporal vector" set to "CVSS:3.0/E:P/RL:O/RC:C") Plugin Feed: 202404021234