It was found that RHSA-2018:2918 did not fully fix CVE-2018-16509. An attacker could possibly exploit another variant of the flaw and bypass the -dSAFER protection to, for example, execute arbitrary shell commands via a specially crafted PostScript document. This only affects ghostscript 9.07 as shipped with Red Hat Enterprise Linux 7.
The product implements a protection mechanism that relies on a list of inputs (or properties of inputs) that are not allowed by policy or otherwise require other action to neutralize before additional processing takes place, but the list is incomplete.
The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.