Bug 2516609 (CVE-2026-72186)

Summary: CVE-2026-72186 kernel: ntfs: make system files immutable to prevent corruption
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's NTFS driver. A local user could exploit this by writing to specific system files, such as $Bitmap, which are exposed through the show_sys_files interface. This unauthorized write access can lead to file system corruption and potentially cause a system deadlock, impacting data integrity and system availability.
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Description OSIDB Bzimport 2026-08-15 06:21:43 UTC 
In the Linux kernel, the following vulnerability has been resolved:

ntfs: make system files immutable to prevent corruption

When a system file such as $Bitmap is exposed via show_sys_files and
written from userspace, the volume is corrupted and, because the cluster
allocator scans $Bitmap through the same inode's page cache, a write to
$Bitmap also deadlocks writeback against the folio it already holds locked.

These files are maintained by the driver itself and have no valid reason
to be written through the file interface. Mark base metadata files
(mft_no < FILE_first_user) as immutable during inode read so the VFS
rejects write, mmap, truncate and unlink with -EPERM. Directories are
skipped so the root and $Extend remain usable. Internal metadata updates
do not go through the VFS write path and are unaffected.
Comment 1 Keith Grant 2026-08-18 14:35:22 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026081540-CVE-2026-72186-e2ba@gregkh/T