CVE-2019-15793

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.

Weakness

The product places sensitive information into files or directories that are accessible to actors who are allowed to have access to the files, but not to the sensitive information.

Affected Software

Potential Mitigations

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/95.html

References

• https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/eoan/commit/?id=3644b9d5688da86f18e017c9c580b75cf52927bb
• https://usn.ubuntu.com/usn/usn-4183-1
• https://usn.ubuntu.com/usn/usn-4184-1
• https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/eoan/commit/?id=3644b9d5688da86f18e017c9c580b75cf52927bb
• https://usn.ubuntu.com/usn/usn-4183-1
• https://usn.ubuntu.com/usn/usn-4184-1