USN-4966-1 fixed a vulnerability in libx11. This update provides the corresponding update for Ubuntu 14.04 ESM and Ubuntu 16.04 ESM.
Original advisory details:
It was discovered that libx11 incorrectly validated certain parameter lengths. A remote attacker could possibly use this issue to trick libx11 into emitting extra X protocol requests.
{ "availability": "Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro", "binaries": [ { "libx11-6-udeb": "2:1.6.2-1ubuntu2.1+esm2", "libx11-6-dbg": "2:1.6.2-1ubuntu2.1+esm2", "libx11-xcb1-dbg": "2:1.6.2-1ubuntu2.1+esm2", "libx11-xcb-dev": "2:1.6.2-1ubuntu2.1+esm2", "libx11-xcb1": "2:1.6.2-1ubuntu2.1+esm2", "libx11-doc": "2:1.6.2-1ubuntu2.1+esm2", "libx11-6-udeb-dbgsym": "2:1.6.2-1ubuntu2.1+esm2", "libx11-xcb-dev-dbgsym": "2:1.6.2-1ubuntu2.1+esm2", "libx11-6-dbgsym": "2:1.6.2-1ubuntu2.1+esm2", "libx11-dev": "2:1.6.2-1ubuntu2.1+esm2", "libx11-xcb1-dbgsym": "2:1.6.2-1ubuntu2.1+esm2", "libx11-dev-dbgsym": "2:1.6.2-1ubuntu2.1+esm2", "libx11-6": "2:1.6.2-1ubuntu2.1+esm2", "libx11-data": "2:1.6.2-1ubuntu2.1+esm2" } ] }
{ "availability": "Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro", "binaries": [ { "libx11-6-udeb": "2:1.6.3-1ubuntu2.2+esm1", "libx11-6-dbg": "2:1.6.3-1ubuntu2.2+esm1", "libx11-xcb1-dbg": "2:1.6.3-1ubuntu2.2+esm1", "libx11-xcb-dev": "2:1.6.3-1ubuntu2.2+esm1", "libx11-xcb1": "2:1.6.3-1ubuntu2.2+esm1", "libx11-doc": "2:1.6.3-1ubuntu2.2+esm1", "libx11-6-udeb-dbgsym": "2:1.6.3-1ubuntu2.2+esm1", "libx11-xcb-dev-dbgsym": "2:1.6.3-1ubuntu2.2+esm1", "libx11-6-dbgsym": "2:1.6.3-1ubuntu2.2+esm1", "libx11-dev": "2:1.6.3-1ubuntu2.2+esm1", "libx11-xcb1-dbgsym": "2:1.6.3-1ubuntu2.2+esm1", "libx11-dev-dbgsym": "2:1.6.3-1ubuntu2.2+esm1", "libx11-6": "2:1.6.3-1ubuntu2.2+esm1", "libx11-data": "2:1.6.3-1ubuntu2.2+esm1" } ] }