Local file-creation hang via double dentry cleanup
Published Sep 11, 2026 · Updated Sep 11, 2026
Double cleanup in Linux kernel OverlayFS 6.18 allows local users to hang later file creation after a casefold-mismatched copy-up. ovl_create_real calls end_creating on the new dentry in the S_IFDIR mismatch branch and again at its common error exit, unlocking and dropping the same objects twice. An unprivileged local user must alter the mounted overlay work subdirectory's casefold state; the next copy-up leaves later creation blocked on its parent lock.
Summary
What happened
Double cleanup in Linux kernel OverlayFS 6.18 allows local users to hang later file creation after a casefold-mismatched copy-up. ovl_create_real calls end_creating on the new dentry in the S_IFDIR mismatch branch and again at its common error exit, unlocking and dropping the same objects twice. An unprivileged local user must alter the mounted overlay work subdirectory's casefold state; the next copy-up leaves later creation blocked on its parent lock.
The record
- CVE
- CVE-2026-89767
- Published
- Sep 11, 2026
- Updated
- Sep 11, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- T1499
- Attack vector
- local
- Privileges
- authenticated
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=6.18
- Affected versionversion=dfc7da402ccc92d6e4b01a4778a3f15f2496b9af <077ab8985ee278c3d8618182d335b0f0cd919e16
- Affected versionversion=dfc7da402ccc92d6e4b01a4778a3f15f2496b9af <2fa220bc0f84597cb6de665e5b5021c5901ddf00
- Affected versionversion=dfc7da402ccc92d6e4b01a4778a3f15f2496b9af <b1aa8ab78a8e87aee9e306971465408e059f839a
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
- OverlayFS casefold-mismatch reproducerproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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