An issue was discovered in shadow 4.5. newgidmap (in shadow-utils) is setuid and allows an unprivileged user to be placed in a user namespace where setgroups(2) is permitted. This allows an attacker to remove themselves from a supplementary group, which may allow access to certain filesystem paths if the administrator has used "group blacklisting" (e.g., chmod g-rwx) to restrict access to paths. This flaw effectively reverts a security feature in the kernel (in particular, the /proc/self/setgroups knob) to prevent this sort of privilege escalation.

Affected: Ubuntu:Pro:14.04:LTS: shadow, Ubuntu:Pro:16.04:LTS: shadow, Ubuntu:18.04:LTS: shadow

It was discovered that shadow incorrectly handled certain inputs. An attacker could possibly use this issue to cause a crash or expose sensitive information. This issue only affected Ubuntu 14.04 ESM and Ubuntu 16.04 ESM. (CVE-2017-12424)

It was discovered that shadow incorrectly handled certain inputs. An attacker could possibly use this issue to expose sensitive information. (CVE-2018-7169)