Allocation of Resources Without Limits or Throttling in LibVNCServer - CVE-2020-14405

Vulnerability identifier: #VU29374

CSH Severity: Medium

CVSS v4: 5.9 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2020-14405

CWE-ID: CWE-770

Exploitation vector: Remote access

Exploit availability: No public exploit available

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.

LibVNCServer
libvncserver (Alpine package)
libvncserver (Red Hat package)
libvncclient1 (Ubuntu package)
libvncserver1 (Ubuntu package)
Red Hat Enterprise Linux for x86_64
Red Hat CodeReady Linux Builder for ARM 64
Red Hat CodeReady Linux Builder for Power, little endian
Red Hat CodeReady Linux Builder for x86_64
Red Hat Enterprise Linux for ARM 64
Red Hat Enterprise Linux for Power, little endian
Red Hat Enterprise Linux for IBM z Systems
Ubuntu
SIMATIC ITC2200 PRO
SIMATIC ITC2200
SIMATIC ITC1900 PRO
SIMATIC ITC1900
SIMATIC ITC1500 PRO
SIMATIC ITC1500

Install updates from vendor's website.

LibVNCServer - update to 0.9.13
libvncserver (Alpine package) - update to 0.9.13-r0
libvncserver (Red Hat package) - update to 0.9.11-17.el8
SIMATIC ITC2200 PRO - update to
libvncclient1 (Ubuntu package) - addressed in versions 0.9.10+dfsg-3ubuntu0.16.04.5, 0.9.11+dfsg-1ubuntu1.3, 0.9.12+dfsg-9ubuntu0.2
libvncserver1 (Ubuntu package) - addressed in versions 0.9.10+dfsg-3ubuntu0.16.04.5, 0.9.11+dfsg-1ubuntu1.3, 0.9.12+dfsg-9ubuntu0.2
SIMATIC ITC2200 PRO - update to 3.2.1.0
SIMATIC ITC2200 - update to 3.2.1.0
SIMATIC ITC1900 PRO - update to 3.2.1.0
SIMATIC ITC1900 - update to 3.2.1.0
SIMATIC ITC1500 PRO - update to 3.2.1.0
SIMATIC ITC1500 - update to 3.2.1.0

• https://github.com/LibVNC/libvncserver/commit/8937203441ee241c4ace85da687b7d6633a12365
• https://github.com/LibVNC/libvncserver/compare/LibVNCServer-0.9.12...LibVNCServer-0.9.13

• Multiple vulnerabilities in LibVNCServer
• Allocation of Resources Without Limits or Throttling in libvncserver (Alpine package)
• Red Hat Enterprise Linux 8 update for libvncserver
• Multiple vulnerabilities in Siemens SIMATIC ITC
• Ubuntu update for libvncserver