External risk intelligence

Linux Kernel SCTP Association Deletion Race Condition

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2026-89479

This vulnerability affects the Linux kernel's SCTP implementation. While SCTP is a network protocol, it is not as ubiquitous as TCP or UDP. Exposure depends on whether an application specifically utilizes SCTP and if that port is reachable from the public internet. Because it requires specific protocol support and configuration, it is not a universally exposed service by default.

Use After Free

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

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A vulnerability has been addressed in the Linux kernel's Stream Control Transmission Protocol (SCTP) implementation. This issue could allow an attacker to disrupt services or gain unauthorized access by sending specially crafted packets. The primary concern is confirming if your organization utilizes SCTP and if it is exposed to potential threats.

Network packets could disrupt services or grant access.
Confirms relevance and exposure for SCTP users.
Verify if your SCTP implementation is affected.

Attack Path

How an attacker could exploit the issue

An attacker could send specially crafted SCTP packets to a Linux system. These packets, when processed by the kernel's SCTP networking component, could exploit a flaw in how the kernel handles the deletion of network associations. This could allow an attacker to trigger a use-after-free condition, potentially leading to system instability or remote code execution.

Network exposure required.
Malicious SCTP packets trigger vulnerability.
Risk of system instability or code execution.

Live Threat

Current exploitation, exposure, and threat context

When supported by the advisory, this vulnerability could affect the Linux kernel's handling of network packets within the SCTP protocol. If an attacker sends specially crafted packets, it may lead to the processing of packets by deleted associations, potentially impacting service behavior.

System data and service integrity.
Specially crafted network packets.
Service disruption or unexpected behavior.

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability impacts the Linux kernel's Stream Control Transmission Protocol (SCTP) implementation. Identifying which systems utilize SCTP, confirming their external reachability and business criticality, and locating the accountable owner are the initial steps. Subsequently, a risk-based remediation plan should be developed, potentially involving coordination with the Linux distribution vendor if direct patching is not feasible.

Own the issue by the Linux infrastructure team.
Verify SCTP usage and external exposure.
Plan for vendor-supported kernel updates.

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 affected by CVE-2026-89479?

SCTP, or Stream Control Transmission Protocol, is a transport layer protocol used alongside TCP and UDP. It is designed to handle multiple data streams simultaneously and is often found in telecommunications, specialized networking equipment, and certain high-availability server applications that require robust, reliable message-based communication.

How would you describe the weakness in CVE-2026-89479?

This vulnerability involves a use-after-free condition. In programming, this means the system continues to use a piece of memory after it has already been released or deleted. In this specific case, the Linux kernel mistakenly tries to process incoming network data using an SCTP association that was already destroyed, which can lead to system instability or unpredictable behavior.

What triggers this SCTP vulnerability?

An attacker must send a specially crafted sequence of network packets that force the system to delete an SCTP association while simultaneously attempting to process further data for that same connection. Legitimate, standard SCTP traffic that does not attempt to manipulate association states in this specific overlapping manner does not trigger the underlying bug.

How relevant is this threat to my environment?

Halo Surface Signal indicates that relevance depends on whether your systems specifically use SCTP and expose that traffic to the internet. Because SCTP is not as common as standard web traffic and often requires explicit configuration, many internal-only or standard web-focused systems may not be reachable or configured to process the malicious packets required for this flaw.

Is there a recommended first step to respond to this issue?

Start by identifying if your infrastructure actively relies on the SCTP protocol. If SCTP is in use, verify which systems are reachable from the public internet, as these are the primary candidates for external exploitation. Once identified, consult your Linux distribution vendor to locate and plan for the application of official kernel patches.

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.