description: On Ubuntu kernels carrying both c914c0e27eb0 and "UBUNTU: SAUCE: overlayfs: Skip permission checking for trusted.overlayfs.* xattrs", an unprivileged user may set privileged extended attributes on the mounted files, leading them to be set on the upper files without the appropriate security checks.
problem types: CWE-863
affected:
{
vendor: Canonical
product: Ubuntu Kernel
platforms: Linux
packageName: Linux
versions:
status: unaffected, version: 0, lessThan: 6.2.0-26.26, versionType: semver
status: unaffected, version: 0, lessThan: 6.0.0-1020.20, versionType: semver
status: unaffected, version: 0, lessThan: 5.4.0-155.172, versionType: semver
defaultStatus: unaffected
}
metrics:
format: CVSS
cvssV3_1: [
version: 3.1
attackVector: LOCAL
attackComplexity: LOW
privilegesRequired: LOW
userInteraction: NONE
scope: UNCHANGED
confidentialityImpact: HIGH
integrityImpact: HIGH
availabilityImpact: HIGH
vectorString: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
baseScore: 7.8
baseSeverity: HIGH
]
workarounds: If not needed, disable the ability for unprivileged users
to create namespaces. To do this temporarily, do:
sudo sysctl -w kernel.unprivileged_userns_clone=0
To disable across reboots, do:
echo kernel.unprivileged_userns_clone=0 | \
sudo tee /etc/sysctl.d/99-disable-unpriv-userns.conf