An issue was discovered in the Linux kernel through 5.18.9. A type confusion bug in nft_set_elem_init (leading to a buffer overflow) could be used by a local attacker to escalate privileges, a different vulnerability than CVE-2022-32250. (The attacker can obtain root access, but must start with an unprivileged user namespace to obtain CAP_NET_ADMIN access.) This can be fixed in nft_setelem_parse_data in net/netfilter/nf_tables_api.c.
The MITRE CVE dictionary describes this issue as:
An issue was discovered in the Linux kernel through 5.18.9. A type confusion bug in nft_set_elem_init (leading to a buffer overflow) could be used by a local attacker to escalate privileges, a different vulnerability than CVE-2022-32250. (The attacker can obtain root access, but must start with an unprivileged user namespace to obtain CAP_NET_ADMIN access.) This can be fixed in nft_setelem_parse_data in net/netfilter/nf_tables_api.c.
In order to trigger the issue, it requires the ability to create user/net namespaces.
On non-containerized deployments of Red Hat Enterprise Linux 8, 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.
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