Todd Carson discovered some integer overflows in libX11, which could lead to heap corruption when processing crafted messages from an input method.

For Debian 9 stretch, this problem has been fixed in version 2:1.6.4-3+deb9u2.

We recommend that you upgrade your libx11 packages.

For the detailed security status of libx11 please refer to its security tracker page at: https://security-tracker.debian.org/tracker/libx11

Further information about Debian LTS security advisories, how to apply these updates to your system and frequently asked questions can be found at: https://wiki.debian.org/LTS