description: The overlayfs implementation in the linux kernel did not properly validate with respect to user namespaces the setting of file capabilities on files in an underlying file system. Due to the combination of unprivileged user namespaces along with a patch carried in the Ubuntu kernel to allow unprivileged overlay mounts, an attacker could use this to gain elevated privileges.
problem types: CWE-270: Privilege Context Switching Error
affected:
{
product: linux kernel
vendor: Ubuntu
versions:
lessThan: 5.8.0-50.56 , status: affected, version: 5.8 kernel, versionType: custom
lessThan:  5.4.0-72.80 , status: affected, version: 5.4 kernel, versionType: custom
lessThan: 4.15.0-142.146 , status: affected, version: 4.15 kernel, versionType: custom
lessThan:  4.4.0-209.241, status: affected, version: 4.4 kernel, versionType: custom
}
metrics:
cvssV3_1: [
attackComplexity: LOW
attackVector: LOCAL
availabilityImpact: HIGH
baseScore: 8.8
baseSeverity: HIGH
confidentialityImpact: HIGH
integrityImpact: HIGH
privilegesRequired: LOW
scope: CHANGED
userInteraction: NONE
vectorString: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
version: 3.1
]
solutions: Apply https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7c03e2cda4a584cadc398e8f6641ca9988a39d52
workarounds: Disable unprivileged user namespaces.