External risk intelligence

Linux Kernel SCTP Out-of-Bounds Read in COOKIE_ECHO Processing

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2026-53246

This vulnerability affects the SCTP protocol implementation within the Linux kernel. SCTP is commonly used for network-facing services, including telephony and high-availability signaling, which are frequently deployed as internet-reachable services. Because the vulnerability exists in the protocol processing stack at the kernel level, it is reachable by unauthenticated remote network traffic.

Halo Surface Signal: 4 out of 5 — likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

This vulnerability in the Linux kernel's SCTP processing could allow remote attackers to cause memory corruption. While the issue has been resolved, understanding its potential impact on network-facing services is important for confirming relevance.

Kernel flaw allows remote memory corruption.
Affects network services; confirm relevance.
Understand impact on critical services.

Attack Path

How an attacker could exploit the issue

An attacker could exploit this by sending specially crafted network packets to a Linux system running a vulnerable kernel. The system's Stream Control Transmission Protocol (SCTP) handling, specifically when processing a COOKIE_ECHO chunk, could be tricked into reading beyond its allocated memory. This could lead to the disclosure or corruption of sensitive kernel memory.

Network access required.
Malicious SCTP COOKIE_ECHO chunk triggers.
Memory corruption, potential system compromise.

Live Threat

Current exploitation, exposure, and threat context

A flaw in the Linux kernel's handling of SCTP protocol data could allow an attacker to read beyond allocated memory. This may occur when a server processes specific network traffic, potentially leading to memory corruption.

Kernel memory could be read.
Malformed network packets can trigger reads.
System instability or crashes may occur.

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability in the Linux kernel's SCTP implementation requires immediate attention from teams managing network services and core operating system infrastructure. The first practical step is to identify all Linux systems running SCTP, confirm their exposure to the network, and determine their business criticality. Subsequently, accountability for remediation must be established, followed by a risk-based remediation plan, potentially involving vendor coordination or temporary mitigations if immediate patching is not feasible.

Infrastructure and platform teams own remediation.
Verify SCTP network exposure and criticality.
Plan risk-based remediation actions.

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 in the Linux kernel that provides reliable, message-oriented data delivery. It is frequently utilized in specialized network environments, such as telephony signaling, high-availability data centers, and various applications that require robust, multi-stream communication between networked systems.

What happens during this CVE-2026-53246 vulnerability?

This flaw is an out-of-bounds read error occurring during the processing of a COOKIE_ECHO network chunk. Essentially, the kernel fails to verify the length of embedded data, causing it to read past the allocated memory buffer. This memory corruption can lead to system instability, crashes, or the unintended exposure of internal kernel memory contents.

How does an attacker trigger this kernel memory error?

An attacker triggers the vulnerability by sending a specially crafted SCTP packet to a listening server. The flaw specifically resides in how the server parses the COOKIE_ECHO chunk; if the chunk's length field is intentionally inflated, the kernel attempts to access memory outside the valid data range. Legitimate, correctly formatted network traffic does not trigger this issue.

Is my system at risk if it uses SCTP?

Halo Surface Signal indicates this vulnerability is reachable via unauthenticated remote network traffic. Because the kernel processes SCTP at a low level, any Linux system exposing an SCTP-based service to the internet is at higher risk. Internal services may be less exposed, but they remain susceptible if an attacker achieves a foothold on your internal network.

How should I respond to this Linux kernel threat?

First, conduct an audit to identify all Linux systems actively using the SCTP protocol. Prioritize these assets based on their network exposure—focusing on internet-facing services first—and their overall business criticality. Once identified, establish a patching plan to update the affected kernel versions to the resolved releases provided by your 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.