CVE-2023-53566: netfilter: nft_set_rbtree: fix null deref on element insertion

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-10-04 · updated 2026-10-15
Weakness: CWE-476

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.

Affected products

Linux kernel: from 5.10.166 before 5.10.181; from 5.15.91 before 5.15.113; from 6.1.9 before 6.1.30; from 6.2.1 before 6.3.4; 6.2, 6.2-rc6, 6.2-rc7, 6.2-rc8, 6.4-rc1, 6.4-rc2 — fixed in 5.10.181, 5.15.113, 6.1.30, 6.3.4

How to fix

Upgrade to a fixed version: Linux kernel 5.10.181, 5.15.113, 6.1.30, 6.3.4. Check the vendor advisory for mitigations.

References

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