External risk intelligence

Linux Kernel SCTP Double Free Vulnerability.

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2026-64564

The vulnerability exists within the SCTP protocol implementation in the Linux kernel. While SCTP is a network-layer protocol that can be exposed to the internet, it is typically used for specific application-layer communication or internal cluster traffic rather than being a ubiquitously exposed web-facing service by default.

Halo Surface Signal: 3 out of 5 — possibly public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

This vulnerability in the Linux kernel's SCTP protocol could allow an attacker to disrupt network communications by causing system instability. The issue arises from how certain network connection data is managed during deletion requests, potentially leading to critical system errors. The main concern is confirming if this specific protocol is in use within your environment.

Core network protocol flaw found.
Risks system stability and connectivity.
Confirm SCTP protocol usage internally.

Attack Path

How an attacker could exploit the issue

An attacker can reach this vulnerability by sending specially crafted network packets to a system running the Linux kernel. The attack leverages the Stream Control Transmission Protocol (SCTP) to manipulate address configurations. By exploiting how the kernel processes certain SCTP control messages, an attacker can cause critical network structures to be freed prematurely and then re-used, leading to a system crash or potential denial-of-service.

Network access required.
Malicious SCTP control messages trigger vulnerability.
System instability or crash.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability in the Linux kernel's SCTP implementation could allow an attacker to disrupt network services when specific ASCONF message sequences are processed. This disruption could lead to a denial of service by causing network connections to enter an unstable state, making them unusable.

Network association state and availability.
Malformed SCTP packets could trigger the issue.
Denial of service for network communications.

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability in the Linux kernel's SCTP implementation requires immediate attention from infrastructure and platform teams. The first practical step is to identify all systems running the affected kernel version, determine their exposure and criticality, and locate the system owners responsible for remediation. Planning for urgent updates or temporary risk reduction measures should follow this assessment.

Infrastructure and Platform teams own resolution.
Verify affected kernel instances and exposure.
Plan urgent remediation or mitigation.

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.

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Frequently asked questions

What is the Linux kernel SCTP component?

SCTP, or Stream Control Transmission Protocol, is a transport-layer protocol within the Linux kernel. It is designed to move data reliably between networked systems, often used for specialized communication like telecommunications signaling or internal high-availability cluster traffic rather than standard web browsing.

What does CVE-2026-64564 mean for system stability?

This vulnerability involves a memory management flaw where the system prematurely releases network path information. By sending specific message sequences, an attacker can trick the kernel into using this freed memory. This leads to a memory corruption state, which typically results in the system crashing or becoming unresponsive.

How is this SCTP vulnerability triggered?

An attacker triggers this by sending a specially crafted sequence of network control messages known as ASCONF. The bug specifically occurs when a 'Delete IP' request targets a transport path already being processed by the system. Normal SCTP traffic that does not include these malformed address-deletion sequences will not trigger the flaw.

Do I need to worry about this if my system is internal?

Yes, but your risk profile depends on usage. Halo Surface Signal notes that while SCTP is often used for internal cluster traffic, it remains a network-layer protocol. If your internal systems rely on SCTP for service-to-service communication, they could be targets for an attacker who has already gained a foothold within your network.

When should I prioritize responding to this CVE?

You should prioritize this if your infrastructure relies heavily on SCTP for critical services. First, audit your environment to identify which systems are running the affected kernel versions and verify if they utilize SCTP. Once identified, consult your platform team to schedule the necessary kernel updates to patch the memory management logic.

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.