External risk intelligence

Linux Kernel SCTP Use-After-Free Vulnerability

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2026-74586

The vulnerability exists within the Linux kernel SCTP implementation, which is a protocol-level component. While network-reachable, SCTP is typically used in specific telecommunications or data center environments rather than as a general-purpose, internet-facing web service. Public exposure is uncommon, and most SCTP traffic is restricted to internal or controlled network segments.

Use After Free

Halo Surface Signal: 2 out of 5 — less likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A vulnerability in the Linux kernel's SCTP component could allow an authenticated remote attacker to cause a denial-of-service condition. This issue arises from improper handling of transport connections during the configuration of SCTP associations. While the technical details involve memory management, the high-level implication is a potential disruption of services relying on this kernel functionality. The main concern is confirming relevance and exposure within your specific operating environments.

Kernel flaw could disrupt services.
Important for secure, specific network services.
Confirm if your Linux systems use SCTP.

Attack Path

How an attacker could exploit the issue

An attacker needs to be authenticated and able to send SCTP protocol messages to a vulnerable Linux system. By sending a specially crafted ASCONF message, the attacker can trick the system into using a freed memory location when it tries to send a heartbeat to a newly added peer. This can lead to the system crashing or behaving unexpectedly.

Authenticated network access required.
Specially crafted ASCONF messages.
System instability and potential crash.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability could allow an authenticated SCTP peer to cause a use-after-free condition, potentially leading to system instability or data corruption. This occurs when a peer sends a malformed ASCONF chunk that manipulates the transport state, causing the kernel to attempt to access freed memory.

System stability and network communications.
Authenticated peers sending malformed ASCONF.
System crashes or data corruption.

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability affects the Linux kernel's SCTP implementation. Infrastructure or platform teams managing systems utilizing SCTP are likely responsible for this issue. The immediate practical step is to identify all systems running the affected kernel version, assess their exposure and criticality, and then coordinate a maintenance window for remediation.

Kernel owners must verify affected systems.
Confirm SCTP usage and network exposure.
Plan and schedule remediation actions.

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-2026-74586?

SCTP (Stream Control Transmission Protocol) is a transport layer protocol used to manage network connections. It is often employed in telecommunications, data centers, and specialized high-availability environments that require reliable message delivery. The Linux kernel implements this protocol to handle data transmission for applications that rely on it.

What kind of vulnerability is CVE-2026-74586?

This vulnerability is a use-after-free issue. In technical terms, it occurs when the kernel continues to use a memory reference after that memory has been released. In this specific case, the kernel fails to clear a pointer to a network transport that it has already deleted, later attempting to access that freed memory, which can lead to system instability or crashes.

How can an attacker trigger this vulnerability?

An attacker must be an authenticated peer capable of sending specific SCTP protocol messages. By sending a crafted ASCONF chunk that adds and then removes a network transport in a particular sequence, an attacker can trick the system into keeping a stale pointer. Simply having network access is not enough; the attacker must be able to authenticate and manipulate the SCTP association state.

Is my system at risk according to Halo Surface Signal?

Halo Surface Signal identifies this as unlikely to be internet-facing because SCTP is generally restricted to internal or specialized network segments rather than general-purpose web traffic. You should care if your infrastructure uses SCTP for internal data center communications or telecommunications services, as these are the environments where the risk is most relevant.

What are the first steps to address this CVE?

Start by identifying all Linux systems in your environment that are actively using SCTP. Once identified, work with your infrastructure or platform teams to assess the criticality of these services. Plan a maintenance window to update the affected kernel versions, as patching the kernel is the standard way to resolve these types of underlying memory management flaws.

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.