CVE-2023-3777: 
Linux Kernel vulnerability analysis and mitigation

A use-after-free vulnerability (CVE-2023-3777) was discovered in the Linux kernel's netfilter: nftables component. The vulnerability was identified when nftables_delrule() is flushing table rules, where it fails to check whether the chain is bound and the chain's owner rule can release the objects in certain circumstances. The issue was fixed in commit 6eaf41e87a223ae6f8e7a28d6e78384ad7e407f8 (Kernel Commit).

The vulnerability exists in the netfilter subsystem of the Linux kernel. When flushing table rules, the nftablesdelrule() function fails to properly check bound chains, leading to a use-after-free condition. The vulnerability has been assigned a CVSS v3.1 base score of 7.8 HIGH with the vector string CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H (NVD).

The vulnerability can be exploited to achieve local privilege escalation. This is particularly concerning for users with CAPNETADMIN capability in any user or network namespace, as they could potentially elevate their privileges on the system (Debian Security).

The primary mitigation is to upgrade the kernel to a version containing the fix (commit 6eaf41e87a223ae6f8e7a28d6e78384ad7e407f8). For systems that cannot be immediately updated, it is recommended to disable the ability for unprivileged users to create namespaces by setting 'kernel.unprivilegedusernsclone=0' (Ubuntu Security).