CVE-2026-68095
Received Received - Intake

Race Condition in Linux Kernel FUSE-URING

Vulnerability report for CVE-2026-68095, 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: fuse-uring: fix race between registration and connection abortion This fixes this race: - thread a: io_uring_enter -> register sqe -> fuse_uring_create_ring_ent -> allocate ent but doesn't grab queue_ref yet - thread b: fuse_conn_destroy() -> fuse_chan_abort() -> fuse_uring_abort() is a no-op due to queue ref being 0 - thread a: grabs the queue_ref, queue_ref is now 1, rest of fuse_uring_do_register() logic executes - thread b: fuse_chan_abort() returns, fuse_chan_wait_aborted() now runs and calls "wait_event(ring->stop_waitq, atomic_read(&ring->queue_refs) == 0);" The abort/unmount thread will hang indefinitely in unkillable state as nothing will decrement queue_refs or wake stop_waitq, and the ring, queue, and ent are leaked. Fix this by checking fch->connected under fch->lock after the created ent has grabbed a ref count on the queue. This ensures that in the scenario above, it is guaranteed that we either release the queue ref and wake up stop_waitq (in case fuse_chan_wait_aborted() is already waiting) in fuse_uring_do_register() when we detect !fch->connected, or if the connection is aborted after the check, it is guaranteed that the async teardown worker will be running in the background cleaning up ents and decrementing the ent's ref on the queue, which will unblock the eventual queue and ring teardown.

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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 vulnerability in the Linux kernel involves a race condition in the fuse-uring subsystem. It occurs when one thread registers a new I/O ring while another thread attempts to abort the connection. The race can cause the aborting thread to hang indefinitely, leaking memory and system resources because the queue reference count is not properly managed.

Detection Guidance

This vulnerability is specific to the Linux kernel's fuse-uring component and may not have direct network detection methods. Monitor kernel logs for fuse-related errors or hangs during io_uring operations. Check for processes stuck in unkillable states or excessive memory usage by fuse-related threads.

Impact Analysis

This vulnerability can lead to system hangs during I/O operations, causing unresponsive applications or system freezes. It may also result in memory leaks, degrading system performance over time. Users could experience disruptions in file system operations or applications relying on io_uring.

Mitigation Strategies

Update the Linux kernel to the latest stable version that includes the fix for this vulnerability. If immediate patching is not possible, consider disabling fuse-uring functionality temporarily until the patch can be applied.

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