#VU48699 Division by zero in LibVNCServer - CVE-2020-25708

Vulnerability identifier: #VU48699

Vulnerability risk: Medium

CVSSv4.0: 6.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2020-25708

CWE-ID: CWE-369

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 perform a denial of service (DoS) attack.

The vulnerability exists due to divide by zero error when processed by the VNC server, would lead to a floating point exception, resulting in a denial of service. A remote attacker can pass specially crafted file to the application and crash it.

Mitigation
Install update from vendor's website.

Vulnerable software versions

LibVNCServer: 0.9.0 - 0.9.12

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External links
https://bugzilla.redhat.com/show_bug.cgi?id=1896739
https://github.com/LibVNC/libvncserver/issues/409
https://github.com/LibVNC/libvncserver/commit/673c07a75ed844d74676f3ccdcfdc706a7052dba

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

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