#VU22957 Memory leak in LibVNCServer - CVE-2019-15681

Vulnerability identifier: #VU22957

Vulnerability risk: Medium

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

CVE-ID: CVE-2019-15681

CWE-ID: CWE-401

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 gain access to sensitive information on the target system.

The vulnerability exists due memory leak in VNC server code. A remote attacker can read stack memory and disclose sensitive information.

Combined with another vulnerability, it can be used to leak stack memory and bypass ASLR.

Mitigation
Install update from vendor's website.

Vulnerable software versions

LibVNCServer: 0.9.0 - 0.9.12

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External links
https://github.com/LibVNC/libvncserver/commit/d01e1bb4246323ba6fcee3b82ef1faa9b1dac82a
https://ics-cert.kaspersky.com/reports/2019/11/22/vnc-vulnerability-research/
https://lists.debian.org/debian-lts-announce/2019/10/msg00039.html
https://lists.debian.org/debian-lts-announce/2019/10/msg00042.html

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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.