Vulnerability Details 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.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.001
EPSS Ranking 16.2%
CVSS Severity
CVSS v3 Score 6.5
CVSS v2 Score 4.6
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
Products affected by CVE-2019-15793
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cpe:2.3:o:canonical:ubuntu_linux:18.04
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cpe:2.3:o:canonical:ubuntu_linux:19.04
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cpe:2.3:o:linux:linux_kernel:5.0
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cpe:2.3:o:linux:linux_kernel:5.3