CVE-2023-2640
First published: Tue Jun 06 2023(Updated: )
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.
Credit: security@ubuntu.com security@ubuntu.com security@ubuntu.com
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Canonical Ubuntu Linux | =23.04 | |
| ubuntu/linux | <6.2.0-26.26 | 6.2.0-26.26 |
| ubuntu/linux-aws | <6.2.0-1008.8 | 6.2.0-1008.8 |
| ubuntu/linux-aws-5.19 | <5.19.0-1029.30~22.04.1 | 5.19.0-1029.30~22.04.1 |
| ubuntu/linux-aws-6.2 | <6.2.0-1008.8~22.04.1 | 6.2.0-1008.8~22.04.1 |
| ubuntu/linux-azure | <6.2.0-1008.8 | 6.2.0-1008.8 |
| ubuntu/linux-azure-6.2 | <6.2.0-1008.8~22.04.1 | 6.2.0-1008.8~22.04.1 |
| ubuntu/linux-azure-fde-6.2 | <6.2.0-1008.8~22.04.1 | 6.2.0-1008.8~22.04.1 |
| ubuntu/linux-gcp | <6.2.0-1010.10 | 6.2.0-1010.10 |
| ubuntu/linux-gcp-5.19 | <5.19.0-1030.32~22.04.1 | 5.19.0-1030.32~22.04.1 |
| ubuntu/linux-gcp-6.2 | <6.2.0-1010.10~22.04.1 | 6.2.0-1010.10~22.04.1 |
| ubuntu/linux-hwe-5.19 | <5.19.0-50.50 | 5.19.0-50.50 |
| ubuntu/linux-hwe-6.2 | <6.2.0-26.26~22.04.1 | 6.2.0-26.26~22.04.1 |
| ubuntu/linux-ibm | <6.2.0-1006.6 | 6.2.0-1006.6 |
| ubuntu/linux-kvm | <6.2.0-1009.9 | 6.2.0-1009.9 |
| ubuntu/linux-lowlatency | <6.2.0-1009.9 | 6.2.0-1009.9 |
| ubuntu/linux-lowlatency-hwe-5.19 | <5.19.0-1030.30 | 5.19.0-1030.30 |
| ubuntu/linux-lowlatency-hwe-6.2 | <6.2.0-1009.9~22.04.1 | 6.2.0-1009.9~22.04.1 |
| ubuntu/linux-oem-6.0 | <6.0.0-1020.20 | 6.0.0-1020.20 |
| ubuntu/linux-oem-6.1 | <6.1.0-1019.19 | 6.1.0-1019.19 |
| ubuntu/linux-oracle | <6.2.0-1008.8 | 6.2.0-1008.8 |
| ubuntu/linux-raspi | <6.2.0-1009.11 | 6.2.0-1009.11 |
| ubuntu/linux-riscv | <6.2.0-27.28.1 | 6.2.0-27.28.1 |
| debian/linux | 4.19.249-2 4.19.304-1 5.10.209-2 5.10.205-2 6.1.76-1 6.1.85-1 6.6.15-2 6.7.12-1 |
Remedy
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
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Reference Links
- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-2640
- https://ubuntu.com/security/notices/USN-6250-1
- https://lists.ubuntu.com/archives/kernel-team/2023-July/140923.html
- https://wiz.io/blog/ubuntu-overlayfs-vulnerability
- https://launchpad.net/bugs/cve/CVE-2023-2640
- https://security-tracker.debian.org/tracker/CVE-2023-2640
- https://ubuntu.com/security/notices/USN-6248-1
- https://ubuntu.com/security/notices/USN-6260-1
- https://ubuntu.com/security/notices/USN-6285-1
- https://www.cve.org/CVERecord?id=CVE-2023-2640
- https://nvd.nist.gov/vuln/detail/CVE-2023-2640
- https://git.kernel.org/linus/c914c0e27eb0843b7cf3bec71d6f34d53a3a671e
- https://git.kernel.org/linus/local-CVE-2023-2640-fix-1|local-CVE-2023-2640-fix-2
- https://ubuntu.com/security/CVE-2023-2640
Frequently Asked Questions
What is CVE-2023-2640?
CVE-2023-2640 is a vulnerability in Ubuntu kernels that allows an unprivileged user to set privileged extended attributes on mounted files without appropriate security checks.
What is the severity of CVE-2023-2640?
The severity of CVE-2023-2640 is high with a CVSS score of 7.8.
Which software is affected by CVE-2023-2640?
Ubuntu Linux 23.04, ubuntu/linux 6.2.0-26.26, ubuntu/linux-hwe-5.19 5.19.0-50.50, and other Ubuntu packages are affected by CVE-2023-2640.
How can I fix CVE-2023-2640?
To fix CVE-2023-2640, update your Ubuntu kernel and packages to the recommended versions mentioned in the Ubuntu Security Notice (USN-6250-1).
Where can I find more information about CVE-2023-2640?
You can find more information about CVE-2023-2640 on the MITRE CVE website, Ubuntu Security Notice (USN-6250-1), and the Ubuntu kernel-team mailing list.
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