CVE-2023-4015

A use-after-free flaw was found in the Linux kernel's netfilter: nf_tables component, which can be exploited to achieve local privilege escalation. On an error when building a nftables rule, deactivating immediate expressions in nft_immediate_deactivate() can unbind the chain and objects can be deactivated but used later.

Exploiting this flaw will require CAP_NET_ADMIN access privilege in any user or network namespace and on non-containerized deployments of Red Hat Enterprise Linux, you can disable user namespaces by setting user.max_user_namespaces to 0:

 echo "user.max_user_namespaces=0" > /etc/sysctl.d/userns.conf
 sysctl -p /etc/sysctl.d/userns.conf

On containerized deployments such as Red Hat OpenShift Container Platform, do not use this mitigation as the functionality is needed to be enabled.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is to skip loading the affected module "netfilter" onto the system till we have a fix available, this can be done by a blacklist mechanism, this will ensure the driver is not loaded at the boot time.

How do I blacklist a kernel module to prevent it from loading automatically?
https://access.redhat.com/solutions/41278