CVE-2026-89681
Received Received - Intake

Race Condition in Linux Kernel NFS Server

Vulnerability report for CVE-2026-89681, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.

Publication date: 2026-09-11

Last updated on: 2026-09-11

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: nfsd: fix layout fence worker double-reference race The workqueue core clears WORK_STRUCT_PENDING before the callback is invoked, so delayed_work_pending() in lm_breaker_timedout() can return false while the fence worker is already running. This lets the breaker take a duplicate sc_count reference and schedule a new worker that coalesces with the in-progress one. The extra reference is never put, leaking the layout stateid. Replace the racy delayed_work_pending() check with an ls_fence_inflight boolean set atomically with refcount_inc_not_zero() under ls_lock, and cleared under ls_lock before the final nfs4_put_stid() on the dispose path; the retry path intentionally retains it. Remove the self-rearm mod_delayed_work() at the top of the worker.

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Meta Information

Published
2026-09-11
Last Modified
2026-09-11
Generated
2026-09-12
AI Q&A
2026-09-12
EPSS Evaluated
N/A
NVD
EUVD

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

Helpful Resources

Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel involves a race condition in the NFS server's layout fence worker. The issue occurs because the workqueue core clears a flag before the worker callback runs, causing a delayed work check to incorrectly indicate the worker is not pending. This leads to a duplicate reference being taken on a layout stateid, which is never released, causing a memory leak in the layout stateid.

Detection Guidance

This vulnerability is specific to the Linux kernel's NFS server implementation and does not have a direct detection method via network commands. It requires kernel-level inspection for signs of layout stateid leaks or duplicate worker references. Check kernel logs for NFS-related errors or warnings using dmesg or journalctl.

Impact Analysis

This vulnerability could lead to resource exhaustion on systems running affected Linux kernel versions with NFS server functionality enabled. The leaked layout stateid may cause memory leaks, potentially degrading system performance or leading to crashes if the issue persists over time.

Mitigation Strategies

Apply the latest Linux kernel patches that address this issue. Monitor NFS server performance and logs for abnormal behavior. If using a vulnerable kernel version, consider temporarily disabling NFS server services until patched.

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