OpenSSH < 7.2 X11Forwarding Fallback Bypass Vulnerability
Medium Nessus Network Monitor Plugin ID 9311
SynopsisThe remote SSH server may be affected by an X11Forwarding fallback bypass vulnerability.
DescriptionOpenSSH contains a flaw in ssh(1) that is triggered when it falls back from untrusted X11 forwarding to trusted forwarding when the X server disables the SECURITY extension. This may potentially result in X11 connections not being trusted.
Note: PVS has solely relied on the banner of the SSH client to perform this check. Any backported patches or workarounds such as recompiling or edited configurations are not observable through the banner.
SolutionUpgrade to OpenSSH version 7.2 or later.