CVE-2026-43084
Analyzed Analyzed - Analysis Complete
Use-After-Free in Linux Kernel nfnetlink_queue

Publication date: 2026-05-06

Last updated on: 2026-06-05

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: netfilter: nfnetlink_queue: make hash table per queue Sharing a global hash table among all queues is tempting, but it can cause crash: BUG: KASAN: slab-use-after-free in nfqnl_recv_verdict+0x11ac/0x15e0 [nfnetlink_queue] [..] nfqnl_recv_verdict+0x11ac/0x15e0 [nfnetlink_queue] nfnetlink_rcv_msg+0x46a/0x930 kmem_cache_alloc_node_noprof+0x11e/0x450 struct nf_queue_entry is freed via kfree, but parallel cpu can still encounter such an nf_queue_entry when walking the list. Alternative fix is to free the nf_queue_entry via kfree_rcu() instead, but as we have to alloc/free for each skb this will cause more mem pressure.
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Meta Information
Published
2026-05-06
Last Modified
2026-06-05
Generated
2026-06-16
AI Q&A
2026-05-06
EPSS Evaluated
2026-06-15
NVD
CVE-2026-43084
EUVD
EUVD-2026-27578
Affected Vendors & Products
Showing 3 associated CPEs
Vendor Product Version / Range
linux linux_kernel From 6.12.75 (inc) to 6.12.83 (exc)
linux linux_kernel From 6.18.14 (inc) to 6.18.24 (exc)
linux linux_kernel From 6.19.4 (inc) to 6.19.14 (exc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-416 The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.
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Executive Summary

This vulnerability exists in the Linux kernel's netfilter nfnetlink_queue component. It arises because a global hash table is shared among all queues, which can lead to a crash due to a use-after-free bug. Specifically, the structure nf_queue_entry is freed using kfree, but a parallel CPU might still access this freed entry when traversing the list, causing a kernel crash.

The issue occurs in the function nfqnl_recv_verdict, and the problem is related to memory management and concurrency. An alternative fix involves using kfree_rcu() to free nf_queue_entry, but this would increase memory pressure because allocations and frees happen for each skb.

Impact Analysis

This vulnerability can cause the Linux kernel to crash due to a use-after-free error in the netfilter nfnetlink_queue subsystem. Such crashes can lead to system instability, denial of service, and potential disruption of network packet processing.

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