CVE-2023-53566 netfilter: nft_set_rbtree: fix null deref on element insertion
A null pointer dereference in the Linux kernel's netfilter subsystem allows local attackers to cause a system crash via specific set element insertions.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2023-53566?
CVE-2023-53566 is a high-severity vulnerability in Linux kernel, published on 4 Oct 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
netfilter: nft_set_rbtree: fix null deref on element insertion
There is no guarantee that rb_prev() will not return NULL in nft_rbtree_gc_elem():
general protection fault, probably for non-canonical address 0xdffffc0000000003: 0000 [#1] PREEMPT SMP KASAN KASAN: null-ptr-deref in range [0x0000000000000018-0x000000000000001f] nft_add_set_elem+0x14b0/0x2990 nf_tables_newsetelem+0x528/0xb30
Furthermore, there is a possible use-after-free while iterating, 'node' can be free'd so we need to cache the next value to use.
Weakness: CWE-476
Which versions are affected by CVE-2023-53566?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2023-53566?
Apply the vendor's patch.
Is CVE-2023-53566 being exploited?
There is no known exploitation of CVE-2023-53566 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2023-53566, DEBIAN-CVE-2023-53566, GHSA-pcw3-hvmm-479h, UBUNTU-CVE-2023-53566.