SB2020063001 - Multiple vulnerabilities in LibVNCServer

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Main Vulnerability Database SB2020063001

SB2020063001 - Multiple vulnerabilities in LibVNCServer

Published: June 30, 2020

Security Bulletin ID SB2020063001
Severity
High
Patch available
YES
Number of vulnerabilities 14
Exploitation vector Remote access
Highest impact Code execution

Breakdown by Severity

High 29% Medium 50% Low 21%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 14 secuirty vulnerabilities.


1) Integer overflow (CVE-ID: CVE-2019-20788)

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to integer overflow in libvncclient/cursor.c  when processing large height or width values. A remote attacker can trick the victim to connect to a malicious VNC server, trigger integer overflow and execute arbitrary code on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.


2) Memory leak (CVE-ID: CVE-2018-21247)

The vulnerability allows a remote attacker to gain access to sensitive information.

The vulnerability exists due memory leak within the ConnectToRFBRepeater() function in  libvncclient/rfbproto.c. A remote attacker can trick the victim to connect to a malicious VNC server, trigger the memory leak and gain access to sensitive information on the client's system.


3) NULL pointer dereference (CVE-ID: CVE-2020-14396)

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to a NULL pointer dereference error in libvncclient/tls_openssl.c. A remote attacker can trick the victim to connect to a malicious server and perform a denial of service (DoS) attack.


4) NULL pointer dereference (CVE-ID: CVE-2020-14397)

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to a NULL pointer dereference error in libvncserver/rfbregion.c. A remote attacker can perform a denial of service (DoS) attack.


5) Infinite loop (CVE-ID: CVE-2020-14398)

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to infinite loop in libvncclient/sockets.c when closing TCP connections. A remote attacker can consume all available system resources and cause denial of service conditions.


6) Information disclosure (CVE-ID: CVE-2020-14399)

The vulnerability allows a remote user to gain access to potentially sensitive information.

The vulnerability exists due to byte-aligned data is accessed through uint32_t pointers in libvncclient/rfbproto.c. A remote authenticated user can gain unauthorized access to sensitive information on the system.


7) Information disclosure (CVE-ID: CVE-2020-14400)

The vulnerability allows a remote user to gain access to potentially sensitive information.

The vulnerability exists due to byte-aligned data is accessed through uint16_t pointers in libvncserver/translate.c. A remote authenticated user can gain unauthorized access to sensitive information on the system.


8) Integer overflow (CVE-ID: CVE-2020-14401)

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to integer overflow in libvncserver/scale.c when processing data passed via pixel_value. A remote attacker can pass specially crafted data to the application, trigger integer overflow and execute arbitrary code on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.


9) Buffer overflow (CVE-ID: CVE-2020-14402)

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to a boundary error when processing encodings in libvncserver/corre.c. A remote attacker can pass specially crafted data to the server, trigger memory corruption and execute arbitrary code on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.


10) Buffer overflow (CVE-ID: CVE-2020-14403)

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to a boundary error when processing encodings in libvncserver/hextile.c. A remote attacker can pass specially crafted data to the server, trigger memory corruption and execute arbitrary code on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.


11) Buffer overflow (CVE-ID: CVE-2020-14404)

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to a boundary error when processing encodings in libvncserver/rre.c. A remote attacker can pass specially crafted data to the server, trigger memory corruption and execute arbitrary code on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.


12) Allocation of Resources Without Limits or Throttling (CVE-ID: CVE-2020-14405)

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists in libvncclient/rfbproto.c due to LibVNCServer does not limit TextChat size.A remote attacker who controls a malicious VNC server can send large amounts of data to the client application and perform a denial of service (DoS) attack.


13) Buffer overflow (CVE-ID: CVE-2019-20839)

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to a boundary when processing long socket filename in libvncclient/sockets.c in LibVNCServer. A remote attacker can rick the victim to connect to server using a specially crafted configuration file, trigger buffer overflow and execute arbitrary code on the target system.


14) Buffer overflow (CVE-ID: CVE-2019-20840)

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to a boundary error within hybiReadAndDecode() in libvncserver/ws_decode.c. A remote attacker can create a specially crafted request to the affected LibVNCServer installation and crash the service.


Remediation

Install update from vendor's website.

References