External risk intelligence

Linux Kernel IPv6 Fragment Accounting Flaw

CVE advisoryKnown Exploit

CVE-2026-53362

This vulnerability exists within the Linux kernel internal memory management and IPv6 networking stack. Exploitation requires an unprivileged local user to execute specific system calls (UDPv6 sockets with MSG_MORE and MSG_SPLICE_PAGES) on the host. It is not remotely reachable over the network and does not involve an internet-facing service or appliance.

Out-of-bounds Write

Linux Kernel

6.0 to before 6.1.1776.2 to before 6.6.1446.7 to before 6.12.956.13 to before 6.18.386.19 to before 7.1.3

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 vulnerability has been identified in the Linux kernel's handling of IPv6 packet data, specifically within its memory allocation process. This issue, if exploited, could allow an unprivileged user to write data beyond allocated memory buffers, potentially impacting system stability and security. While the vulnerability requires local access and specific conditions to trigger, it affects a core component of the Linux operating system.

Memory handling flaw in Linux kernel.
Affects system stability and security.
Confirm relevance and exposure.

Attack Path

How an attacker could exploit the issue

An attacker can exploit this vulnerability by manipulating memory accounting within the Linux kernel's IPv6 networking subsystem. This is achievable by an unprivileged local user who can trigger a specific condition involving UDPv6 sockets and certain socket options. If successful, this manipulation can lead to memory corruption, potentially allowing the attacker to gain elevated privileges on the system.

Requires local, unprivileged access.
Triggered via UDPv6 socket with specific options.
Leads to memory corruption and privilege escalation.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability could affect the integrity and availability of system memory within the Linux kernel's IPv6 networking stack. Under specific conditions, an unprivileged local user could trigger a buffer overflow by manipulating packet data during fragmented packet reassembly. This could lead to memory corruption, potentially impacting service behavior.

Kernel memory integrity and availability.
Local user triggers buffer overflow.
Potential for memory corruption.

Operational Fix

Recommended remediation, mitigation, and detection steps

In a real-world scenario, the Linux kernel's networking and infrastructure teams are likely responsible for addressing this vulnerability. The first practical step is to identify all systems running the affected Linux kernel versions, confirm their exposure and criticality, and then ascertain the specific owner accountable for each system or service. This will enable a risk-based remediation plan.

Ownership: Infrastructure and platform teams.
Verify: System exposure and criticality.
Action: Plan updates based on risk.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

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Frequently asked questions

What is the Linux kernel and where does CVE-2026-53362 fit in?

The Linux kernel is the core foundation of the operating system that manages hardware resources for software. This CVE describes a memory accounting error within its networking stack, specifically impacting how IPv6 data is processed when it is split into multiple pieces (fragments) during transmission.

What is the weakness class for this vulnerability?

This vulnerability is classified as CWE-122, which refers to a heap-based buffer overflow. In plain terms, the kernel miscalculates the amount of memory needed for incoming network data, causing it to write information into adjacent memory areas it shouldn't access.

How can an attacker trigger this memory corruption?

An attacker needs local access to the system to run specialized software. The issue is triggered by making specific requests—using UDPv6 sockets combined with certain memory-handling flags (MSG_MORE and MSG_SPLICE_PAGES)—that confuse the kernel's memory allocation logic. It cannot be triggered by simply sending network traffic to the machine.

Is my system at risk according to Halo Surface Signal?

According to Halo Surface Signal, this is highly unlikely to be a remote threat. Because the vulnerability requires an attacker to already have local access and execute specific system calls, it is not reachable over the network and does not involve internet-facing services.

How should I respond to this Linux kernel advisory?

Start by identifying all systems in your environment that are running the affected Linux kernel versions. Once you have a list of assets, prioritize them based on their criticality and work with your infrastructure or platform teams to plan and apply the necessary security updates provided by your Linux distribution vendor.

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.