CVE-2026-53168
Received Received - Intake
FUSE Pagecache Operation Rejection in Linux Kernel

Publication date: 2026-06-25

Last updated on: 2026-06-25

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: fuse: reject fuse_notify() pagecache ops on directories The operations FUSE_NOTIFY_STORE and FUSE_NOTIFY_RETRIEVE allow the FUSE daemon to actively write/read pagecache contents. For directories with FOPEN_CACHE_DIR, the pagecache is used as kernel-internal cache storage, and userspace is not supposed to have direct access to this cache - in particular, fuse_parse_cache() will hit WARN_ON() if the cache contains bogus data. Reject FUSE_NOTIFY_STORE and FUSE_NOTIFY_RETRIEVE on anything other than regular files with -EINVAL.
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Meta Information
Published
2026-06-25
Last Modified
2026-06-25
Generated
2026-06-25
AI Q&A
2026-06-25
EPSS Evaluated
N/A
NVD
CVE-2026-53168
EUVD
EUVD-2026-39259
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *
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Exploitability
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KEV
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CWE ID Description
CWE-UNKNOWN
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Executive Summary

This vulnerability exists in the Linux kernel's FUSE (Filesystem in Userspace) implementation. Specifically, it involves the operations FUSE_NOTIFY_STORE and FUSE_NOTIFY_RETRIEVE, which allow the FUSE daemon to actively write to or read from the pagecache contents.

The issue arises because for directories with the FOPEN_CACHE_DIR flag, the pagecache is used as an internal kernel cache, and userspace should not have direct access to this cache. If the cache contains invalid data, the kernel triggers warnings.

The vulnerability was fixed by rejecting FUSE_NOTIFY_STORE and FUSE_NOTIFY_RETRIEVE operations on anything other than regular files, returning an error (-EINVAL) if attempted on directories or other types.

Impact Analysis

This vulnerability could allow a FUSE daemon to improperly write or read pagecache data for directories, which is intended to be protected and only used internally by the kernel.

Such unauthorized access to the pagecache could lead to kernel warnings or instability, and potentially cause incorrect behavior or data corruption in the filesystem cache.

Mitigation Strategies

The vulnerability has been resolved by rejecting FUSE_NOTIFY_STORE and FUSE_NOTIFY_RETRIEVE operations on anything other than regular files with an error -EINVAL.

To mitigate this vulnerability, ensure your Linux kernel is updated to a version that includes this fix.

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