CVE-2023-2640

kernel: overlayfs: In Ubuntu skip permission checking for trusted.overlayfs.* xattrs

Published Jul 26, 2023 CVSS 3.1 · 7.8 High EPSS 15.2% KEV · Not listed
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.

Remediation

Vendor Workaround

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

Tracking

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Advisories

Source ID Title
Ubuntu USN Ubuntu USN USN-6248-1 Linux kernel (OEM) vulnerabilities
Ubuntu USN Ubuntu USN USN-6250-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-6260-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-6285-1 Linux kernel (OEM) vulnerabilities
Ubuntu USN Ubuntu USN USN-8255-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-8255-2 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-8255-3 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-8275-1 Linux kernel (Xilinx ZynqMP) vulnerabilities
Ubuntu USN Ubuntu USN USN-8297-1 Linux kernel (GCP) vulnerabilities
Ubuntu USN Ubuntu USN USN-8439-1 Linux kernel (Oracle) vulnerabilities
History
Type Values Removed Values Added
Metrics epss

{'score': 0.91874}

epss

{'score': 0.92037}

Type Values Removed Values Added
First Time appeared Canonical ubantu Kernel
CPEs cpe:2.3:o:canonical:ubantu_kernel:*:*:*:*:*:*:*:*
Vendors & Products Canonical ubantu Kernel
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
canonical
Published
Updated
Oct 23, 2024, 2:59 PM
Reserved
May 10, 2023, 9:23 PM
Status
Modified
Published
Jul 26, 2023, 2:15 AM
Modified
Jun 17, 2026, 5:53 AM
Severity
Important
Public date
Jul 6, 2023, 12:00 AM