CVE-2026-43028: Linux Kernel Netfilter missing null-termination in x_tables

CVE-2026-43028 · Severity: high · CVSS 7.1 · Published 2026-05-01

A vulnerability exists in the Linux kernel's networking subsystem (Netfilter) which is used for firewalling and traffic filtering. An attacker with local access to the system could provide specially crafted input that lacks proper termination, potentially leading to system instability or unauthorized access to sensitive kernel memory. This issue also affects certain Siemens industrial controllers that utilize the Linux kernel.

Technologies: Linux Kernel, Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP, Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP, Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP. Vendors: Linux, Siemens.

Quick answers

Is CVE-2026-43028 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-43028 being exploited in the wild.
How severe is CVE-2026-43028?
High severity, with a CVSS score of 7.1, published 1 May 2026.
Which products and versions are affected?
Linux Kernel Fixed in 6.7.12, 6.8.3, and other stable branches via backports; Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP V3.1.5, V3.1.6; Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP V3.1.5, V3.1.6; Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP V3.1.5, V3.1.6.
Is there a fix for CVE-2026-43028?
A patch was published on 2026-04-01: Initial patch in Linux kernel mainline Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-43028 attacked?
It is attacked with local access, in an operating system.
Am I affected by CVE-2026-43028?
Check whether you run Linux Kernel, Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP, Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP or one of the others listed 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 Netfilter x_tables component of the Linux kernel arises from a failure to validate that string inputs (such as cgroup paths or rate estimator names) are null-terminated before they are passed to functions expecting C-style strings. Specifically, the 'xt_cgroup' and 'xt_rateest' modules were found to be vulnerable. A local attacker can exploit this by providing a name that lacks a null terminator, causing the kernel to read past the intended buffer. This can result in a kernel information leak or a denial-of-service (system crash). The fix involves adding 'strnlen' checks to ensure names are properly terminated within their allocated buffer size.

Affected products

  • Linux Linux Kernel Fixed in 6.7.12, 6.8.3, and other stable branches via backports
  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP V3.1.5, V3.1.6
  • Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP V3.1.5, V3.1.6
  • Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP V3.1.5, V3.1.6

Timeline

  • 2026-05-01: disclosed
  • 2026-04-01: patched: Initial patch in Linux kernel mainline
  • 2026-05-01: advisory

References

This page as Markdown. Free to reuse under CC BY 4.0 with a link back.