CVE-2019-15793: Canonical Ubuntu Linux

High severity, CVSS 8.8. EPSS: 0.7% chance of exploitation in the next 30 days.

In shiftfs, a non-upstream patch to the Linux kernel included in the Ubuntu 5.0 and 5.3 kernel series, several locations which shift ids translate user/group ids before performing operations in the lower filesystem were translating them into init_user_ns, whereas they should have been translated into the s_user_ns for the lower filesystem. This resulted in using ids other than the intended ones in the lower fs, which likely did not map into the shifts s_user_ns. A local attacker could use this to possibly bypass discretionary access control permissions.

Affected products

• Canonical Ubuntu Linux: version 18.04 only; version 19.04 only
• Linux Linux Kernel: version 5.0 only; version 5.3 only

Published 2020-04-24. Last modified 2026-06-17.