External risk intelligence

Linux Kernel SCTP Uninitialized Memory Read Vulnerability

CVE advisorySeverity: CRITICAL (CVSS 9.1)

CVE-2026-53225

The vulnerability exists in the Linux kernel's SCTP implementation. SCTP is a transport-layer protocol that can be exposed to the internet in specific deployments (such as telecommunications or specialized services), but it is not a ubiquitous internet-facing service like HTTP or SSH. Exposure depends heavily on the specific application or network configuration utilizing SCTP.

Linux Kernel

2.6.25 to before 5.10.2595.11 to before 5.15.2105.16 to before 6.1.1766.2 to before 6.6.1436.7 to before 6.12.946.13 to before 6.18.366.19 to before 7.0.137.1

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

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

This CVE addresses an issue within the Linux kernel's SCTP implementation where an unauthenticated peer could send specially crafted data, potentially causing the system to read uninitialized memory. This could lead to a denial-of-service or other unintended behavior. The primary concern is confirming if your specific environment utilizes SCTP in a manner that could be exposed to such a threat.

Unauthenticated peers could read unintended memory.
It affects a specific network protocol, not all Linux systems.
Confirm SCTP usage and exposure in your environment.

Attack Path

How an attacker could exploit the issue

An unauthenticated attacker could exploit this vulnerability by sending a specially crafted, truncated SCTP chunk over the network. The Linux kernel's SCTP processing code, specifically in the `__sctp_rcv_asconf_lookup` function, trusts a declared length for an address parameter. If this chunk is malformed, the function may read past the intended data, accessing uninitialized memory.

Network access to SCTP.
Send malformed SCTP chunk.
Read uninitialized memory.

Live Threat

Current exploitation, exposure, and threat context

When supported by the advisory, an unauthenticated peer could cause the receive path to read uninitialized memory. This occurs when a truncated ASCONF chunk declares an IPv6 address parameter but only includes the header, leading the system to read beyond the expected data.

Kernel memory could be exposed.
Malicious peer sends truncated data.
System may crash or behave unexpectedly.

Operational Fix

Recommended remediation, mitigation, and detection steps

The Linux kernel's SCTP implementation is affected by an uninitialized memory read vulnerability. Initial triage should focus on identifying and confirming the presence of the affected technology, assessing its reachability and business criticality, and then identifying the accountable owner for remediation planning.

Identify affected Linux kernel deployments.
Verify SCTP network exposure and criticality.
Plan vendor coordination for 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-2026-53225?

SCTP (Stream Control Transmission Protocol) is a transport-layer protocol within the Linux kernel. It acts similarly to TCP or UDP, providing a way for applications to exchange data across a network. It is often used in telecommunications, specialized networking services, or specific high-availability applications that require reliable message delivery and multi-homing support.

What kind of vulnerability is CVE-2026-53225?

This is an uninitialized memory read vulnerability. In programming, this means the software attempts to read data from a memory location before a value has been properly assigned to it. When triggered, the system retrieves whatever random data happens to be sitting in that memory space, which can lead to system instability, memory disclosure, or unexpected behavior.

How does an attacker trigger this memory read bug?

An attacker triggers this by sending a malformed, truncated network packet to a system running the vulnerable SCTP stack. The flaw occurs because the kernel relies on a header length declared by the incoming packet without verifying that the full data packet actually exists. It does not trigger if the packet is well-formed or if the system does not process these specific ASCONF chunks.

Is my system at risk according to Halo Surface Signal?

The risk depends on whether your infrastructure exposes SCTP to the internet. Because SCTP is not as common as standard web traffic like HTTP, Halo Surface Signal flags this as 'Possible' rather than universal. You should investigate your specific network configurations to see if any services are actively listening for SCTP traffic, as those are the primary candidates for potential impact.

What are the first steps to address this CVE?

Your priority is to identify which of your Linux systems are running services that utilize the SCTP protocol. Once identified, evaluate whether these services are reachable from untrusted networks. Engage your system administrators to review your Linux distribution's security bulletins, as they will provide the patched kernel versions required to resolve this memory handling error.

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.