CVE-2026-43084
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Use-After-Free in Linux Kernel nfnetlink_queue

Publication date: 2026-05-06

Last updated on: 2026-05-06

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
2026-05-06
Generated
2026-05-07
AI Q&A
2026-05-06
EPSS Evaluated
N/A
NVD
CVE-2026-43084
EUVD
EUVD-2026-27578
Affected Vendors & Products
Showing 2 associated CPEs
Vendor Product Version / Range
linux_kernel linux_kernel *
linux linux_kernel *
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-UNKNOWN
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AI Powered Q&A
Can you explain this vulnerability to me?

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.


How can this vulnerability impact me? :

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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