#VU29385 Integer overflow in LibVNCServer - CVE-2019-20788

Vulnerability identifier: #VU29385

Vulnerability risk: Medium

CVSSv4.0: 4.4 [CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2019-20788

CWE-ID: CWE-190

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
LibVNCServer
Server applications / Remote management servers, RDP, SSH

Vendor: LibVNC

Description

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.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

LibVNCServer: 0.9.0 - 0.9.12

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External links
https://lists.opensuse.org/opensuse-security-announce/2020-05/msg00027.html
https://github.com/LibVNC/libvncserver/commit/54220248886b5001fbbb9fa73c4e1a2cb9413fed

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.