ARP Header Manipulation Vulnerability in Linux Kernel Products
CVE-2026-53266

8.8HIGH

Key Information:

Vendor: Linux
Status: Linux
Vendor: CVE Published:; 25 June 2026

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What is CVE-2026-53266?

CVE-2026-53266 is a notable vulnerability found in the Linux kernel, specifically relating to its handling of ARP header manipulation within the netfilter bridge component. The vulnerability allows for the optional rewriting of the ARP sender hardware address in a manner that could be exploited by threat actors. If not adequately addressed, this vulnerability could permit unauthorized modifications to network traffic, undermining the integrity and security of data traversing the network.

This flaw arises due to the way the Linux kernel manages skbuff, a core data structure used for network packets. The method employed for ensuring that the necessary data segments are writable can lead to unintended manipulation of ARP packets. Given that ARP is crucial for resolving IP addresses to MAC addresses in a local network, a successful exploitation could facilitate various types of man-in-the-middle attacks or spoofing techniques, disrupting normal network operations.

Potential Impact of CVE-2026-53266

Man-in-the-Middle Attacks: Exploiting this vulnerability can allow attackers to intercept and alter network traffic, which could lead to unauthorized access to sensitive information transmitted over the network, thereby compromising data integrity.
Network Disruption: The ability to manipulate ARP traffic can disrupt normal network operations by redirecting or dropping packets, potentially causing denial of service conditions for users and affecting connected systems.
Data Exfiltration: By leveraging the vulnerability, unauthorized users could reroute legitimate traffic, consequently gaining access to confidential data or introducing malicious payloads into the network, enabling further exploitation or data breaches.

CISA has reported CVE-2026-53266

CISA provides regional cyber and physical services to support security and resilience across the United States. CISA monitor the most dangerious vulnerabilities and have identifed CVE-2026-53266 as being exploited but is not known by the CISA to be used in ransomware campaigns. This is subject to change at pace

The CISA's recommendation is: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

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Affected Version(s)

Linux 63137bc5882a1882c553d389fdeeeace86ee1741

Linux 63137bc5882a1882c553d389fdeeeace86ee1741 < 76280b78cc9f23bdc6438e10ad6dff148ef8375b

Linux 63137bc5882a1882c553d389fdeeeace86ee1741

News Articles

BleepingComputer

CVE-2026-53266 CVE-2025-39964

CISA alerts of active exploitation of three Linux kernel flaws

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) is warning that hackers are exploiting three Linux kernel vulnerabilities, one of them rated critical.

1 hour ago