SB2020070626 - Fedora 31 update for libvncserver
Published: July 6, 2020 Updated: April 25, 2025
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 3 secuirty vulnerabilities.
1) Buffer overflow (CVE-ID: CVE-2019-20839)
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.
2) Memory leak (CVE-ID: CVE-2018-21247)
The vulnerability allows a remote attacker to gain access to sensitive information.
The vulnerability exists due memory leak within the ConnectToRFBRepeater() function in libvncclient/rfbproto.c. A remote attacker can trick the victim to connect to a malicious VNC server, trigger the memory leak and gain access to sensitive information on the client's system.
3) Out-of-bounds write (CVE-ID: CVE-2017-18922)
The vulnerability allows a remote non-authenticated attacker to execute arbitrary code.
It was discovered that websockets.c in LibVNCServer prior to 0.9.12 did not properly decode certain WebSocket frames. A malicious attacker could exploit this by sending specially crafted WebSocket frames to a server, causing a heap-based buffer overflow.
Remediation
Install update from vendor's website.