External risk intelligence

Linux Kernel ksmbd Use-After-Free via Async Crypto

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2026-53046

This vulnerability affects ksmbd, an in-kernel SMB server implementation. SMB services are commonly deployed to provide network file sharing and are frequently exposed or reachable across enterprise networks, including scenarios where such services may be accessible via internet-facing gateways or managed storage interfaces.

Use After Free

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

A security vulnerability has been identified in the Linux kernel's ksmbd component, which handles SMB file sharing. This issue, if exploited, could lead to a system crash. The main concern is confirming its relevance and exposure within your environment.

A kernel flaw could cause system instability.
Critical systems may be at risk if exposed.
Verify impact and exposure to affected systems.

Attack Path

How an attacker could exploit the issue

An attacker could exploit this vulnerability by sending specially crafted network requests to a system running a vulnerable version of the Linux kernel's SMB server component (ksmbd). This could lead to a crash, potentially allowing an attacker to cause a denial of service or possibly gain elevated privileges. The vulnerability arises from improper handling of asynchronous cryptographic operations, where memory is freed prematurely while hardware operations are still in progress.

Network access required.
Triggers a crash in kernel.
Leads to denial of service or code execution.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability could affect the stability of systems running the Linux kernel's ksmbd service when it interacts with specific hardware crypto engines. When an asynchronous crypto operation is in progress, the system may incorrectly free memory that is still in use by the hardware, leading to a crash.

System crashes.
Use-after-free due to crypto operations.
Service instability or denial of service.

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability in the Linux kernel's ksmbd component, which handles SMB traffic and utilizes hardware crypto acceleration, requires a coordinated response. Infrastructure and platform teams responsible for the Linux kernel and its associated services are likely to be involved. The initial focus should be on identifying all systems running the affected ksmbd functionality, assessing their network exposure and business criticality, and then engaging the accountable system owners to plan remediation.

Platform and infrastructure teams own the issue.
Verify ksmbd exposure and criticality first.
Plan remediation based on asset risk.

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 ksmbd component?

ksmbd is an in-kernel server implementation that allows a Linux system to share files and printers over the network using the SMB protocol. It is built directly into the kernel to provide high-performance file sharing capabilities, often used in enterprise storage or specialized networking environments that require native SMB support.

How does CVE-2026-53046 lead to a system crash?

This vulnerability involves a memory management error known as a use-after-free. When ksmbd uses a Qualcomm crypto engine for security operations, it incorrectly frees memory while the hardware is still accessing it. This mismatch causes the kernel to attempt to reference the now-deleted data, resulting in a NULL pointer crash.

Do I need specific hardware to trigger this bug?

Yes, this specific issue occurs when the system relies on asynchronous hardware crypto engines, specifically the Qualcomm Crypto Engine (QCE). Environments that do not use this specific hardware for SMB cryptographic operations are not subject to this particular memory-handling flaw.

Is my system at risk according to Halo Surface Signal?

Halo Surface Signal notes that ksmbd is often deployed for network file sharing and is frequently accessible across enterprise networks. Systems are at higher risk if they are exposed to the public internet or managed through gateways, as the vulnerability is reachable via network requests.

What is the first step to address this kernel issue?

Begin by identifying all systems in your environment that are running the ksmbd service. Once mapped, assess which of these assets have network exposure and hold critical business data. Coordinate with your platform or infrastructure teams to review kernel update availability and schedule maintenance for the affected servers.

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.