CVE-2024-27020: 
Linux Kernel vulnerability analysis and mitigation

CVE-2024-27020 is a vulnerability discovered in the Linux kernel's netfilter component, specifically in the nf_tables subsystem. The vulnerability was disclosed on May 1, 2024, affecting the Linux kernel versions from 3.13 up to versions before 4.19.313, 5.4.275, 5.10.216, 5.15.157, and their corresponding branches (NVD).

The vulnerability stems from a potential data race condition in the __nft_expr_type_get() function. The issue occurs when nft_unregister_expr() can run concurrently with __nft_expr_type_get(), without proper protection when iterating over the nf_tables_expressions list. This vulnerability has been assigned a CVSS v3.1 base score of 7.0 (High), with the vector string CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H (NVD).

The vulnerability could potentially lead to data corruption or system instability due to the race condition in the netfilter subsystem. The high CVSS score indicates that successful exploitation could result in high impacts on confidentiality, integrity, and availability of the affected system (NVD).

The vulnerability requires local access and has high attack complexity. An attacker needs low privileges but no user interaction to exploit this vulnerability. The attack vector is local, meaning the attacker needs to have prior access to the targeted system (NVD).

The vulnerability has been fixed by implementing proper RCU (Read-Copy-Update) protection mechanisms. The fix involves using list_for_each_entry_rcu() to iterate over nf_tables_expressions list in __nft_expr_type_get(), and using rcu_read_lock() in the caller nft_expr_type_get() to protect the entire type query process. Multiple Linux distributions have released patches to address this vulnerability (Kernel Patch).