# CVE-2026-43450: netfilter: nfnetlink_cthelper: fix OOB read in nfnl_cthelper_dump_table()

Status: published. Published: 2026-05-08. Updated: 2026-11-06.

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

## Remediation

No remediation reported in collected sources

## Affected products and versions

- Linux / Linux: ≥ 12f7a505331e6b2754684b509f2ac8f0011ce644; < 0605e1985a95d4334a67869aee45a47e82301abf (affected, git); ≥ 12f7a505331e6b2754684b509f2ac8f0011ce644; < 92441f6d9405a0c18d03f278b395e782f79a4a30 (affected, git); ≥ 12f7a505331e6b2754684b509f2ac8f0011ce644; < 3cc328ffc32ddb389cba7b78b6aa95d995c2876e (affected, git); ≥ 12f7a505331e6b2754684b509f2ac8f0011ce644; < 4a1f6ee69267a5f524102c028981410eeacfa3da (affected, git); ≥ 12f7a505331e6b2754684b509f2ac8f0011ce644; < 894c5780ddadd5fde0e16f66587918e6be1504c4 (affected, git); ≥ 12f7a505331e6b2754684b509f2ac8f0011ce644; < 05018cd9370f77bb18fbf6e15ff33c7a06f10b3c (affected, git); ≥ 12f7a505331e6b2754684b509f2ac8f0011ce644; < 61b3a1f8621df1a5928118313f133996f6a786db (affected, git); ≥ 12f7a505331e6b2754684b509f2ac8f0011ce644; < 6dcee8496d53165b2d8a5909b3050b62ae71fe89 (affected, git). Source: CNA: Linux
- Linux / Linux: 3.6 (affected); ≥ 0; < 3.6 (unaffected, semver); ≥ 5.10.253; ≤ 5.10.* (unaffected, semver); ≥ 5.15.203; ≤ 5.15.* (unaffected, semver); ≥ 6.1.167; ≤ 6.1.* (unaffected, semver); ≥ 6.6.130; ≤ 6.6.* (unaffected, semver); ≥ 6.12.78; ≤ 6.12.* (unaffected, semver); ≥ 6.18.19; ≤ 6.18.* (unaffected, semver); ≥ 6.19.9; ≤ 6.19.* (unaffected, semver); ≥ 7.0; ≤ * (unaffected, original_commit_for_fix). Source: CNA: Linux

## Severity and prioritization

- CISA KEV: No listing in collected sources

- EPSS: 0.13% as of 2026-11-06; percentile 2.79%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: Not reported

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://git.kernel.org/stable/c/0605e1985a95d4334a67869aee45a47e82301abf (CNA: Linux)

- https://git.kernel.org/stable/c/92441f6d9405a0c18d03f278b395e782f79a4a30 (CNA: Linux)

- https://git.kernel.org/stable/c/3cc328ffc32ddb389cba7b78b6aa95d995c2876e (CNA: Linux)

- https://git.kernel.org/stable/c/4a1f6ee69267a5f524102c028981410eeacfa3da (CNA: Linux)

- https://git.kernel.org/stable/c/894c5780ddadd5fde0e16f66587918e6be1504c4 (CNA: Linux)

- https://git.kernel.org/stable/c/05018cd9370f77bb18fbf6e15ff33c7a06f10b3c (CNA: Linux)

- https://git.kernel.org/stable/c/61b3a1f8621df1a5928118313f133996f6a786db (CNA: Linux)

- https://git.kernel.org/stable/c/6dcee8496d53165b2d8a5909b3050b62ae71fe89 (CNA: Linux)

## Provenance

- CNA: Linux: https://www.cve.org/CVERecord?id=CVE-2026-43450; retrieved 2026-11-06; source updated 2026-11-06

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-43450; retrieved 2026-11-06; source updated Not reported

Revision: fda55debc4ba9b75a784ef6a0985190487f4f6fc59ade72b049e8570e1e1d610

Canonical: https://y2.dev/cve/CVE-2026-43450

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