View at Official ubuntu advisory, NVD, CVE.org · CVE detail
Freshness: upstream tracker timestamp is available; use API updated time as primary recency signal.
CVE-2017-12178 medium priority: Ubuntu including 8 source packages (xorg, xorg-hwe-16.04, …), 32 status rows across 4 suites (trusty, upstream, xenial, zesty): DNE 16, released 8, not-affected 5, needs-triage 3.
xorg-x11-server before 1.19.5 had wrong extra length check in ProcXIChangeHierarchy function allowing malicious X client to cause X server to crash or possibly execute arbitrary code.