SEPTEMBER 19, 2026
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Case File

CVE-2026-64263

MEDIUM · CVSS 5.5 EPSS 0.15%

Source: NVD + CISA KEV + EPSS · Published 2026-07-25 · Last synced 2026-08-24

CyberRota Analysis

AI-Generated

The vulnerability affects the Linux kernel's fuse-uring implementation, where improper handling of cancelled entries can lead to a crash due to dereferencing a null pointer. This flaw may impact systems relying on the fuse-uring feature for asynchronous I/O operations, potentially leading to service disruptions. Administrators of Linux systems utilizing this feature should prioritize applying the fix to ensure stability and prevent unexpected crashes.

CVE
CVE-2026-64263
Severity
MEDIUM
CVSS
5.5
EPSS
0.15%
Linux

Original NVD Description

In the Linux kernel, the following vulnerability has been resolved: fuse-uring: fix moving cancelled entry to ent_in_userspace list fuse_uring_cancel() moves entries that are available (these have no reqs attached) to the ent_in_userspace list. ent_list_request_expired() checks the first entry on ent_in_userspace and dereferences ent->fuse_req unconditionally, which will crash on a cancelled entry that was moved to this list. Fix this by freeing the entry and dropping queue_refs directly in fuse_uring_cancel(). This is safe because cancel is the cancel handler itself - after io_uring_cmd_done(), no more cancels will be dispatched for this command, and teardown serializes with cancel via queue->lock. Since cancel now decrements queue_refs, fuse_uring_abort() must no longer gate fuse_uring_abort_end_requests() on queue_refs > 0, as cancelled entries may have already dropped queue_refs while requests are still queued. Remove the gate so abort always flushes requests and stops queues.

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