CVE-2023-2640

Summary

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.

Affected Software

Weaknesses

• CWE-863: CWE-863

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

ADP Enrichment

CVE Program Container

Additional References

• https://ubuntu.com/security/notices/USN-6250-1
• https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-2640
• https://wiz.io/blog/ubuntu-overlayfs-vulnerability
• https://lists.ubuntu.com/archives/kernel-team/2023-July/140923.html

CISA ADP Vulnrichment

• SSVC:
• Exploitation: none
  • Automatable: no
  • Technical Impact: total

References

• https://ubuntu.com/security/notices/USN-6250-1
• https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-2640
• https://wiz.io/blog/ubuntu-overlayfs-vulnerability
• https://lists.ubuntu.com/archives/kernel-team/2023-July/140923.html

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