CVE-2026-68381
Received Received - Intake

Use-After-Free in ksmbd Linux Kernel SMB Server

Vulnerability report for CVE-2026-68381, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.

Publication date: 2026-08-10

Last updated on: 2026-08-10

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: ksmbd: pin conn during async oplock break notification smb2_oplock_break_noti() and smb2_lease_break_noti() store a ksmbd_conn pointer in an async ksmbd_work and then queue that work on ksmbd-io. The work only increments conn->r_count, which prevents teardown from passing the pending-request wait after the increment, but it does not pin the struct ksmbd_conn object. If connection teardown races with an oplock break notification, the last conn reference can be dropped before the queued worker finishes. The worker then uses the freed conn in ksmbd_conn_write() and ksmbd_conn_r_count_dec(). Take a real conn reference when publishing the conn pointer to the async work item, and drop it after the notification work has decremented r_count. Apply the same lifetime rule to lease break notification, which uses the same work->conn pattern.

CVSS Scores

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Meta Information

Published
2026-08-10
Last Modified
2026-08-10
Generated
2026-08-10
AI Q&A
2026-08-10
EPSS Evaluated
N/A
NVD
EUVD

Affected Vendors & Products

Currently, no data is known.

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This is a Linux kernel vulnerability where ksmbd (SMB server implementation) fails to properly pin a connection during async oplock or lease break notifications. The issue occurs when a connection is torn down while an async notification is still pending, leading to use-after-free conditions in ksmbd_conn_write() and ksmbd_conn_r_count_dec().

Detection Guidance

This vulnerability is specific to the Linux kernel's ksmbd implementation and may not have direct detection commands. Monitor kernel logs for smbd-related errors or crashes, especially during oplock or lease break operations. Check for connection teardown issues in ksmbd logs or dmesg output.

Impact Analysis

If exploited, this could allow an attacker to cause a denial of service or execute arbitrary code in the kernel context. Systems using ksmbd for SMB file sharing could be affected if the race condition is triggered.

Mitigation Strategies

Update the Linux kernel to the latest stable version that includes the fix for this vulnerability. If using a distribution kernel, apply the patch from your vendor. Restart affected services or reboot the system to ensure the updated kernel is active.

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