External risk intelligence

Linux Kernel SCTP Use-After-Free Vulnerability

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2026-98548

The vulnerability exists in the Linux kernel SCTP implementation, which is a network protocol. While SCTP is used in various network services, it is not as universally exposed as TCP or UDP services. Reachability depends on the specific host configuration, firewall rules, and whether an application is configured to listen for SCTP traffic. Therefore, it is plausibly reachable but not universally exposed by design.

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

This Linux kernel vulnerability affects the Stream Control Transmission Protocol (SCTP) implementation, potentially allowing unauthenticated attackers to crash systems or execute arbitrary code. The issue arises from a use-after-free condition during packet processing, which could be triggered by a malicious SCTP peer.

A flaw in Linux kernel's SCTP could be exploited.
It can lead to system instability or code execution.
Confirm relevance and exposure for this specific kernel function.

Attack Path

How an attacker could exploit the issue

An attacker could send specially crafted SCTP packets to a Linux system. If the system is running a vulnerable version of the kernel and has SCTP enabled, the attacker can exploit a flaw in how the kernel handles specific error conditions during packet processing. This can lead to the kernel corrupting memory, potentially allowing an attacker to gain control or crash the system.

No special access required.
Malicious SCTP packets trigger vulnerability.
Use-after-free leading to system compromise.

Live Threat

Current exploitation, exposure, and threat context

A malicious SCTP peer, or an unprivileged local user acting as one, could trigger a use-after-free vulnerability within the Linux kernel's SCTP implementation. This occurs when processing specific bundled packets under certain states, potentially leading to system instability or information disclosure.

Kernel memory could be corrupted.
Malicious peers may trigger packet processing errors.
System instability or crashes may occur.

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability impacts the Linux kernel's SCTP implementation, meaning infrastructure and platform teams managing Linux systems are primarily responsible. The first step is to identify all systems running the affected kernel version, confirm SCTP exposure and business criticality, and then assign ownership for remediation.

Infrastructure and platform teams own remediation.
Verify SCTP usage and critical systems first.
Plan coordinated maintenance for patching.

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 SCTP implementation?

SCTP, or Stream Control Transmission Protocol, is a transport layer protocol used alongside TCP and UDP. In the Linux kernel, it manages multi-homed connections—where a single association uses multiple IP addresses. It is commonly utilized by telecommunications, signaling, and specific high-reliability network applications that require ordered message delivery.

What is the vulnerability in CVE-2026-98548?

This is a use-after-free vulnerability. It occurs when the kernel prematurely frees memory associated with a network transport path while still needing it to process subsequent data in the same packet. Because the kernel maintains a pointer to that freed memory, it can inadvertently read or write to it later, causing memory corruption.

How is this SCTP flaw triggered?

An attacker sends a specially crafted, bundled SCTP packet during a specific connection state. The trigger requires the packet to contain both an error report and additional data. If the error causes the kernel to delete the transport path while the packet is still being parsed, the system becomes vulnerable. Simply sending standard SCTP traffic without this specific error-and-data combination does not trigger the flaw.

Is my system reachable via this CVE?

According to Halo Surface Signal, reachability depends on whether your Linux system is configured to listen for SCTP traffic. While the vulnerability is network-based, SCTP is less universally exposed than TCP or UDP. Check your host configurations and firewall rules to determine if any services on your network are actively accepting SCTP connections.

What should I do to address this issue?

Infrastructure teams should first inventory systems running the Linux kernel to identify where SCTP is enabled. Once identified, prioritize critical systems and evaluate whether those services require SCTP. Plan for kernel updates to address the underlying memory management logic, coordinating maintenance windows to minimize disruption to your network environment.

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.