External risk intelligence

Linux Kernel netfilter ARP Rewrite Vulnerability

CVE advisoryKnown Exploit

CVE-2026-53266

This vulnerability resides within the Linux kernel's ebtables networking component, specifically involving internal memory management for socket-buffer fragments. It requires local access or specific, highly privileged configuration to influence kernel-level memory operations, making it inherently internal and not a publicly reachable network service or internet-facing attack surface.

Out-of-bounds Write

Linux Kernel

5.4.73 to before 5.55.8.17 to before 5.95.9.2 to before 5.10.2595.11 to before 5.15.2105.16 to before 6.1.1766.2 to before 6.6.1436.7 to before 6.12.946.13 to before 6.18.366.19 to...

Halo Surface Signal: 1 out of 5 — much less likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A security flaw in the Linux kernel's networking component could allow unauthorized modifications to system memory. This vulnerability is classified as internal, meaning it requires local access to be exploited, and impacts the way the kernel handles network packet data.

Kernel vulnerability affects internal packet rewriting.
Matters due to potential for unauthorized memory access.
Focus on confirming relevance and internal exposure.

Attack Path

How an attacker could exploit the issue

An attacker with local access could exploit this vulnerability by triggering a specific network packet manipulation within the Linux kernel's netfilter bridge component. This involves targeting the ebtables SNAT functionality, where an ARP rewrite operation is mishandled. By crafting a packet that causes the kernel to write data beyond the allocated buffer for the ARP sender hardware address, an attacker could corrupt memory, potentially leading to system compromise.

Local access required to initiate.
Triggered by ARP rewrite in ebtables.
Risk of memory corruption.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability in the Linux kernel's netfilter component could allow an attacker to write data beyond intended memory boundaries when manipulating ARP headers within certain network traffic. This could lead to memory corruption when the ARP sender hardware address is rewritten under specific conditions, particularly when dealing with nonlinear skb fragments backed by splice-imported file pages.

Kernel memory corruption.
Unsafe ARP header rewrite.
Potential system instability.

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability in the Linux kernel's netfilter:bridge component impacts systems running affected kernel versions. Infrastructure and platform teams are likely responsible for managing the kernel. The initial step should be to identify all instances of the affected Linux kernel, determine their business criticality and network reachability, and then confirm the accountable owner for remediation.

Kernel and infrastructure teams own the issue.
Verify kernel version and network exposure.
Plan and execute updates during maintenance.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

Free EASM Trial See How Signal Works

Frequently asked questions

What is the Linux kernel and where does this vulnerability exist?

The Linux kernel is the core foundation of an operating system, managing hardware and system resources. This issue resides specifically within netfilter, a framework that handles network packet filtering and manipulation, particularly in the bridge component that manages traffic between network interfaces.

What does CWE-787 mean regarding CVE-2026-53266?

CWE-787 refers to an out-of-bounds write. In this context, the system fails to properly verify if a memory location is valid before writing data to it. The vulnerability occurs during an ARP (Address Resolution Protocol) header update where the kernel writes data into memory without ensuring that the target area is correctly writable, potentially corrupting adjacent data.

How is this vulnerability triggered?

The flaw is triggered when the kernel performs an ARP sender hardware address rewrite via the ebtables SNAT target. The risk occurs when this specific memory region is located in a nonlinear socket-buffer fragment backed by a splice-imported file page. If the kernel does not ensure this range is writable before the write operation, memory corruption can occur. Standard, simple packets that do not utilize these specific memory conditions do not trigger the bug.

Is my system at risk according to Halo Surface Signal?

Halo Surface Signal classifies this as internal because it requires local access or highly privileged configuration to reach the kernel-level memory operations involved. It is not an internet-facing service or a remote network attack surface. You should prioritize assets where untrusted local users or processes might interact with network bridge configurations.

What should I do if I am running an affected Linux kernel?

First, identify which systems in your environment are running the vulnerable kernel versions. Confirm the ownership of these assets and verify their business criticality. Since this involves a core component, coordinate with your infrastructure or platform teams to plan an update to a patched version during your next scheduled maintenance cycle.

References

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.