CVE-2026-53266: Linux Kernel netfilter improper memory write in ebt_snat ARP rewrite

CVE-2026-53266 · Severity: critical · Exploited in the wild · Published 2026-06-25

The Linux kernel ebtables networking module contains an out-of-bounds memory write vulnerability that allows an attacker to overwrite memory on the system. An attacker with network access could exploit this flaw to execute arbitrary code, crash the system, or gain unauthorized access to sensitive data. This affects older kernel versions and poses a critical risk to systems still running unsupported versions.

Technologies: Linux Kernel. Vendors: Linux.

Quick answers

Is CVE-2026-53266 exploited in the wild?
Yes. CVE-2026-53266 is known to be exploited in the wild, first recorded on 18 September 2026. Treat it as urgent.
How severe is CVE-2026-53266?
Critical severity, published 25 June 2026.
Which products and versions are affected?
Linux Kernel 63137bc5882a to bf84ad7c7a9ede46e31afaa41a1ba06a159e8c87, Multiple versions (end-of-life and end-of-service).
Is there a fix for CVE-2026-53266?
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-2026-53266 attacked?
It is attacked over the network, in an operating system.
Am I affected by CVE-2026-53266?
Check whether you run Linux Kernel or Linux Kernel 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

This vulnerability is a classic out-of-bounds write (CWE-787) in the ebtables SNAT (Source Network Address Translation) target. The flaw occurs when rewriting an ARP (Address Resolution Protocol) sender hardware address into a nonlinear socket-buffer fragment that is backed by a splice-imported file page. The vulnerable code fails to properly validate buffer boundaries before writing, allowing an attacker to overwrite adjacent kernel memory. The attack is network-accessible and does not require prior authentication; an attacker can craft malicious ARP packets to trigger the condition. Successful exploitation could lead to kernel memory corruption, denial of service, or arbitrary code execution with kernel privileges. The vulnerability is known to be actively exploited in the wild. Patched kernel versions are available and users are advised to upgrade immediately.

Affected products

  • Linux Linux Kernel Multiple versions (end-of-life and end-of-service)

Timeline

  • 2026-09-18: disclosed
  • exploited: Known to be actively exploited in the wild

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