CVE-2023-3390

Published: 28 June 2023

A use-after-free vulnerability was found in the Linux kernel's netfilter subsystem in net/netfilter/nf_tables_api.c. Mishandled error handling with NFT_MSG_NEWRULE makes it possible to use a dangling pointer in the same transaction causing a use-after-free vulnerability. This flaw allows a local attacker with user access to cause a privilege escalation issue. We recommend upgrading past commit 1240eb93f0616b21c675416516ff3d74798fdc97.

From the Ubuntu Security Team

It was discovered that the netfilter subsystem in the Linux kernel did not properly handle some error conditions, leading to a use-after-free vulnerability. A local attacker could use this to cause a denial of service (system crash) or possibly execute arbitrary code.

Notes

requires CAP_NET_ADMIN in any namespace

Mitigation

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

Status

Severity score breakdown

References

• https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-3390
• https://git.kernel.org/linus/1240eb93f0616b21c675416516ff3d74798fdc97
• https://kernel.dance/#1240eb93f0616b21c675416516ff3d74798fdc97
• https://ubuntu.com/security/notices/USN-6246-1
• https://ubuntu.com/security/notices/USN-6250-1
• https://ubuntu.com/security/notices/USN-6251-1
• https://ubuntu.com/security/notices/USN-6252-1
• https://ubuntu.com/security/notices/USN-6254-1
• https://ubuntu.com/security/notices/USN-6255-1
• https://ubuntu.com/security/notices/USN-6260-1
• https://ubuntu.com/security/notices/USN-6261-1
• https://ubuntu.com/security/notices/USN-6285-1
• https://ubuntu.com/security/notices/USN-6385-1
• NVD
• Launchpad
• Debian

Bugs

• https://bugzilla.redhat.com/show_bug.cgi?id=2213260