USN-4407-1: LibVNCServer vulnerabilities

01 July 2020

Several security issues were fixed in LibVNCServer.

Releases

Packages

Details

It was discovered that LibVNCServer incorrectly handled decompressing data. An
attacker could possibly use this issue to cause LibVNCServer to crash,
resulting in a denial of service. (CVE-2019-15680)

It was discovered that an information disclosure vulnerability existed in
LibVNCServer when sending a ServerCutText message. An attacker could possibly
use this issue to expose sensitive information. This issue only affected
Ubuntu 19.10, Ubuntu 18.04 LTS, and Ubuntu 16.04 LTS. (CVE-2019-15681)

It was discovered that LibVNCServer incorrectly handled cursor shape updates.
If a user were tricked in to connecting to a malicious server, an attacker
could possibly use this issue to cause LibVNCServer to crash, resulting in a
denial of service, or possibly execute arbitrary code. This issue only
affected Ubuntu 19.10, Ubuntu 18.04 LTS, and Ubuntu 16.04 LTS.
(CVE-2019-15690, CVE-2019-20788)

It was discovered that LibVNCServer incorrectly handled decoding WebSocket
frames. An attacker could possibly use this issue to cause LibVNCServer to
crash, resulting in a denial of service, or possibly execute arbitrary code.
This issue only affected Ubuntu 19.10, Ubuntu 18.04 LTS, and Ubuntu 16.04 LTS.
(CVE-2017-18922)

Update instructions

The problem can be corrected by updating your system to the following package versions:

Ubuntu 20.04
Ubuntu 19.10
Ubuntu 18.04
Ubuntu 16.04

After a standard system update you need to restart LibVNCServer to make
all the necessary changes.

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