CVE-2026-43452 Linux CVE debrief

Who should care

Linux kernel maintainers, distro security teams, embedded Linux vendors, and operators who rely on iptables/nftables or other netfilter-based filtering features, especially on affected kernel release lines.

Technical summary

The affected code path is in netfilter/x_tables option walkers used by xt_tcpudp and xt_dccp. The walker logic advanced with an expression like i += op[i + 1] ? : 1, but when i reached the final byte of the option area, op[i + 1] could be read past the end of the buffer. The resolved fix adds an explicit i == optlen - 1 check before dereferencing op[i + 1]. NVD lists affected Linux kernel ranges across multiple branches, including 2.6.16 through versions before 5.10.253, 5.11 through before 5.15.203, 5.16 through before 6.1.167, 6.2 through before 6.6.130, 6.7 through before 6.12.78, 6.13 through before 6.18.19, 6.19 through before 6.19.9, and early 7.0 release candidates rc1, rc2, and rc3.

Defensive priority

High. This is a kernel-level memory-safety issue in widely deployed networking code, with network-based attack conditions and broad affected version coverage. Patch deployment should be prioritized for internet-facing and multi-tenant systems, then rolled into all supported kernel branches and vendor backports.

Recommended defensive actions

• Apply the vendor/stable kernel updates referenced by the linked patches as soon as practical.
• Verify whether any production kernels fall within the affected version ranges listed by NVD, including vendor backported builds.
• Prioritize remediation on systems that expose netfilter-managed packet filtering or routing paths.
• Track downstream distro advisories for backported fixes if you do not run mainline kernel versions.
• After patching, confirm the running kernel build includes the x_tables walker fix in xt_tcpudp and xt_dccp.

Evidence notes

This debrief is based on the official NVD CVE record and the linked Linux kernel stable patch references. The description in the source item states that xt_tcpudp and xt_dccp option walkers could read op[i + 1] past the end of the option area and that an explicit tail-byte check was added. NVD metadata provides the affected version ranges and CVSS vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H. No KEV listing was provided in the supplied corpus.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.