What’s Vulnerable › Vulnerabilities
CVE-2019-15793: Mishandling of file-system uid/gid with namespaces in shiftfs
- Severity: high (CVSS 8.8 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.7% probability of exploitation in the next 30 days
- Public exploit or detection template: yes
- Published: 2020-04-24 · updated 2026-06-17
- Weakness: CWE-538
Description
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: 18.04, 19.04
- Linux kernel: 5.0, 5.3
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
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