# CVE-2026-43024: Linux Kernel denial of service in netfilter nf_tables

Source: https://junglewise.ai/threats/cve-2026-43024-linux-kernel-denial-of-service-in-netfilter-nf-tables  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-01. Updated: 2026-07-14  
License: CC BY 4.0 with a link back

CVE-2026-43024 · Severity: medium · CVSS 5.5 · Published 2026-05-01

A vulnerability was identified in the Linux kernel's networking subsystem (netfilter) that could allow a local user to cause a system crash. The issue stems from how the system handles specific network filtering instructions that are not intended for direct use. This could lead to a denial-of-service condition, impacting the availability of affected systems, including certain industrial controllers.

Technologies: [Linux Kernel](https://junglewise.ai/threats/technologies/kernel), [Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP](https://junglewise.ai/threats/technologies/simatic-s7-1500-cpu-1518-4-pn-dp-mfp). Vendors: [Linux](https://junglewise.ai/threats/vendors/linux), [Siemens](https://junglewise.ai/threats/vendors/siemens).

## Quick answers

**Is CVE-2026-43024 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-43024 being exploited in the wild.

**How severe is CVE-2026-43024?** Medium severity, with a CVSS score of 5.5, published 1 May 2026.

**Which products and versions are affected?** Linux Kernel All versions prior to the April 2026 patches; Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP V3.1.5, V3.1.6.

**Is there a fix for CVE-2026-43024?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-43024 attacked?** It is attacked with local access, in an operating system.

**Am I affected by CVE-2026-43024?** Check whether you run Linux Kernel or Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A vulnerability in the Linux kernel netfilter subsystem (nf_tables) exists because the nft_verdict_init function in net/netfilter/nf_tables_api.c did not properly validate NF_QUEUE verdicts. While NF_QUEUE is intended to be delivered via the nft_queue expression, an attacker could provide an immediate NF_QUEUE verdict. This is particularly problematic in the ARP family, which does not support queuing but could still reach this code path. A local attacker with sufficient privileges to modify nftables rules can exploit this to trigger unexpected kernel behavior or a denial-of-service (DoS). The issue has been resolved by explicitly rejecting immediate NF_QUEUE verdicts in the verdict initialization logic.

## Affected products

- Linux Linux Kernel All versions prior to the April 2026 patches
- Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP V3.1.5, V3.1.6

## Timeline

- 2026-03-31: other: Patch authored by Pablo Neira Ayuso
- 2026-05-01: disclosed
- 2026-05-01: advisory

## References

- [https://git.kernel.org/stable/c/17dc5d5a935c771338430cbc156a16a51cfd31e8](https://git.kernel.org/stable/c/17dc5d5a935c771338430cbc156a16a51cfd31e8)
- [https://git.kernel.org/stable/c/2f7f825a548be55420f0f5f716f6c27b9d312d3f](https://git.kernel.org/stable/c/2f7f825a548be55420f0f5f716f6c27b9d312d3f)
- [https://git.kernel.org/stable/c/42a47f4b1b7695026ab9bc1bb35d4622b0835c95](https://git.kernel.org/stable/c/42a47f4b1b7695026ab9bc1bb35d4622b0835c95)
- [https://git.kernel.org/stable/c/4b12a3cc3f075e750cc3c5e693fd25fb400af4a2](https://git.kernel.org/stable/c/4b12a3cc3f075e750cc3c5e693fd25fb400af4a2)
- [https://git.kernel.org/stable/c/68390437a998c3f2c57212b413abef5e6d657d88](https://git.kernel.org/stable/c/68390437a998c3f2c57212b413abef5e6d657d88)
- [https://git.kernel.org/stable/c/da107398cbd4bbdb6bffecb2ce86d5c9384f4cec](https://git.kernel.org/stable/c/da107398cbd4bbdb6bffecb2ce86d5c9384f4cec)
- [https://git.kernel.org/stable/c/f140593901724cfbd16597c3a4fcb24a58ae44b0](https://git.kernel.org/stable/c/f140593901724cfbd16597c3a4fcb24a58ae44b0)

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