From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-cve-announce@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@kernel.org>
Subject: CVE-2026-43450: netfilter: nfnetlink_cthelper: fix OOB read in nfnl_cthelper_dump_table()
Date: Fri, 8 May 2026 16:22:59 +0200 [thread overview]
Message-ID: <2026050857-CVE-2026-43450-8919@gregkh> (raw)
From: Greg Kroah-Hartman <gregkh@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
The Linux kernel CVE team has assigned CVE-2026-43450 to this issue.
Affected and fixed versions
===========================
Issue introduced in 3.6 with commit 12f7a505331e6b2754684b509f2ac8f0011ce644 and fixed in 5.10.253 with commit 0605e1985a95d4334a67869aee45a47e82301abf
Issue introduced in 3.6 with commit 12f7a505331e6b2754684b509f2ac8f0011ce644 and fixed in 5.15.203 with commit 92441f6d9405a0c18d03f278b395e782f79a4a30
Issue introduced in 3.6 with commit 12f7a505331e6b2754684b509f2ac8f0011ce644 and fixed in 6.1.167 with commit 3cc328ffc32ddb389cba7b78b6aa95d995c2876e
Issue introduced in 3.6 with commit 12f7a505331e6b2754684b509f2ac8f0011ce644 and fixed in 6.6.130 with commit 4a1f6ee69267a5f524102c028981410eeacfa3da
Issue introduced in 3.6 with commit 12f7a505331e6b2754684b509f2ac8f0011ce644 and fixed in 6.12.78 with commit 894c5780ddadd5fde0e16f66587918e6be1504c4
Issue introduced in 3.6 with commit 12f7a505331e6b2754684b509f2ac8f0011ce644 and fixed in 6.18.19 with commit 05018cd9370f77bb18fbf6e15ff33c7a06f10b3c
Issue introduced in 3.6 with commit 12f7a505331e6b2754684b509f2ac8f0011ce644 and fixed in 6.19.9 with commit 61b3a1f8621df1a5928118313f133996f6a786db
Issue introduced in 3.6 with commit 12f7a505331e6b2754684b509f2ac8f0011ce644 and fixed in 7.0 with commit 6dcee8496d53165b2d8a5909b3050b62ae71fe89
Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.
Unaffected versions might change over time as fixes are backported to
older supported kernel versions. The official CVE entry at
https://cve.org/CVERecord/?id=CVE-2026-43450
will be updated if fixes are backported, please check that for the most
up to date information about this issue.
Affected files
==============
The file(s) affected by this issue are:
net/netfilter/nfnetlink_cthelper.c
Mitigation
==========
The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes. Individual
changes are never tested alone, but rather are part of a larger kernel
release. Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all. If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
https://git.kernel.org/stable/c/0605e1985a95d4334a67869aee45a47e82301abf
https://git.kernel.org/stable/c/92441f6d9405a0c18d03f278b395e782f79a4a30
https://git.kernel.org/stable/c/3cc328ffc32ddb389cba7b78b6aa95d995c2876e
https://git.kernel.org/stable/c/4a1f6ee69267a5f524102c028981410eeacfa3da
https://git.kernel.org/stable/c/894c5780ddadd5fde0e16f66587918e6be1504c4
https://git.kernel.org/stable/c/05018cd9370f77bb18fbf6e15ff33c7a06f10b3c
https://git.kernel.org/stable/c/61b3a1f8621df1a5928118313f133996f6a786db
https://git.kernel.org/stable/c/6dcee8496d53165b2d8a5909b3050b62ae71fe89
reply other threads:[~2026-05-08 14:26 UTC|newest]
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