CVE-2026-43450
Received Received - Intake
Out-of-Bounds Read in Linux Kernel Netfilter nfnetlink_cthelper

Publication date: 2026-05-08

Last updated on: 2026-05-08

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: netfilter: nfnetlink_cthelper: fix OOB read in nfnl_cthelper_dump_table() nfnl_cthelper_dump_table() has a 'goto restart' that jumps to a label inside the for loop body. When the "last" helper saved in cb->args[1] is deleted between dump rounds, every entry fails the (cur != last) check, so cb->args[1] is never cleared. The for loop finishes with cb->args[0] == nf_ct_helper_hsize, and the 'goto restart' jumps back into the loop body bypassing the bounds check, causing an 8-byte out-of-bounds read on nf_ct_helper_hash[nf_ct_helper_hsize]. The 'goto restart' block was meant to re-traverse the current bucket when "last" is no longer found, but it was placed after the for loop instead of inside it. Move the block into the for loop body so that the restart only occurs while cb->args[0] is still within bounds. BUG: KASAN: slab-out-of-bounds in nfnl_cthelper_dump_table+0x9f/0x1b0 Read of size 8 at addr ffff888104ca3000 by task poc_cthelper/131 Call Trace: nfnl_cthelper_dump_table+0x9f/0x1b0 netlink_dump+0x333/0x880 netlink_recvmsg+0x3e2/0x4b0 sock_recvmsg+0xde/0xf0 __sys_recvfrom+0x150/0x200 __x64_sys_recvfrom+0x76/0x90 do_syscall_64+0xc3/0x6e0 Allocated by task 1: __kvmalloc_node_noprof+0x21b/0x700 nf_ct_alloc_hashtable+0x65/0xd0 nf_conntrack_helper_init+0x21/0x60 nf_conntrack_init_start+0x18d/0x300 nf_conntrack_standalone_init+0x12/0xc0
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Meta Information
Published
2026-05-08
Last Modified
2026-05-08
Generated
2026-05-09
AI Q&A
2026-05-08
EPSS Evaluated
N/A
NVD
EUVD
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
linux_kernel linux_kernel *
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-UNKNOWN
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability exists in the Linux kernel's netfilter component, specifically in the nfnetlink_cthelper module within the function nfnl_cthelper_dump_table().

The issue arises because a 'goto restart' statement jumps to a label inside the for loop body incorrectly. When the 'last' helper stored in cb->args[1] is deleted between dump rounds, the condition (cur != last) fails for every entry, so cb->args[1] is never cleared.

As a result, the for loop completes with cb->args[0] equal to nf_ct_helper_hsize, and the 'goto restart' jumps back into the loop body bypassing the bounds check. This causes an 8-byte out-of-bounds read on nf_ct_helper_hash at index nf_ct_helper_hsize.

The intended behavior was for the 'goto restart' to re-traverse the current bucket only while cb->args[0] is within bounds, but it was placed incorrectly after the for loop instead of inside it.


How can this vulnerability impact me? :

This vulnerability can lead to an out-of-bounds read in kernel memory, which may cause system instability or crashes.

An attacker with the ability to trigger this code path could potentially exploit this flaw to read sensitive kernel memory, leading to information disclosure.

While the description does not explicitly mention privilege escalation or remote code execution, out-of-bounds reads in kernel space are serious as they can be leveraged in further attacks.


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