While X11 servers authenticate their clients, X11 clients *do not* authenticate the server. This can be exploited to take control of an X application by impersonating the server it is expecting to connect to.
Public via: https://www.openwall.com/lists/oss-security/2020/11/09/3
Created libX11 tracking bugs for this issue: Affects: fedora-all [bug 1896017] Created xorg-x11-server tracking bugs for this issue: Affects: fedora-all [bug 1896018]
External References: https://www.openwall.com/lists/oss-security/2020/11/09/3
This bug is now closed. Further updates for individual products will be reflected on the CVE page(s): https://access.redhat.com/security/cve/cve-2020-25697
Statement: As per upstream, exploiting this flaw is non-trivial and it requires exact timing on the behalf of the attacker. Many graphical applications exit if their connection to the X server is lost, so a typical desktop session is either impossible or difficult to exploit. There is currently no upstream patch available for this flaw.