Data corruption and write loss via unprotected folios
Published Sep 11, 2026 · Updated Sep 11, 2026
Data corruption in the Linux kernel Btrfs writeback path allows local users to corrupt or lose mmap-backed file data. extent_write_cache_pages() replaced folio_clear_dirty_for_io() with folio_test_dirty(), leaving shared mmap PTEs writable while writeback consumes a folio. Exploitation requires write access to an mmap-backed Btrfs file and winning a writeback race; consequences include invalid checksums, lost writes, and corrupted compressed data.
Summary
What happened
Data corruption in the Linux kernel Btrfs writeback path allows local users to corrupt or lose mmap-backed file data. extent_write_cache_pages() replaced folio_clear_dirty_for_io() with folio_test_dirty(), leaving shared mmap PTEs writable while writeback consumes a folio. Exploitation requires write access to an mmap-backed Btrfs file and winning a writeback race; consequences include invalid checksums, lost writes, and corrupted compressed data.
The record
- CVE
- CVE-2026-89772
- Published
- Sep 11, 2026
- Updated
- Sep 11, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- Unavailable
- Attack vector
- local
- Privileges
- Unavailable
Timeline
How it unfolded
- Sep 11, 2026CVE publishedPublication date reported by the CVE source.
- Sep 11, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=6.13
- Affected versionversion=a4ef54dbb576032ba31a646a5ffc8a26a83cb92c <074c715e0b498891c09fe7f11e1cd9d7a04699bd
- Affected versionversion=a4ef54dbb576032ba31a646a5ffc8a26a83cb92c <5376c9db45368eb210b4d71104ac00a59dc8b6e0
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
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Public exploit references
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Technologies
Your stack
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Your stack
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