Buffer overflow in libvncserver (Alpine package)

1) Buffer overflow

EUVDB-ID: #VU29373

Risk: Medium

CVSSv4.0: 4.8 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2019-20839

CWE-ID: CWE-119 - Memory corruption

Exploit availability: No

Description

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.

Mitigation

Install update from vendor's website.

Vulnerable software versions

libvncserver (Alpine package): 0.9.10-r0 - 0.9.12-r2

CPE2.3

• cpe:2.3:o:alpine:libvncserver_alpine_package:0.9.10-r0:*:*:*:*:alpine_linux:*:3.1
• cpe:2.3:o:alpine:libvncserver_alpine_package:0.9.10-r1:*:*:*:*:alpine_linux:*:3.1
• cpe:2.3:o:alpine:libvncserver_alpine_package:0.9.10-r2:*:*:*:*:alpine_linux:*:3.1

External links

https://git.alpinelinux.org/aports/commit/?id=60d0315bb55d8dd7d0c654dbcf8ca9157bee54f2
https://git.alpinelinux.org/aports/commit/?id=bd5545fe9442912826f75d68a7f88e0a71f0f571

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.