Kernel crash via uninitialized allocated_roots access
Published Dec 4, 2025 · Updated May 11, 2026
NULL-pointer dereference in Linux btrfs 6.8 and later affected branches allows local users to crash the kernel during a subvolume mount. The btrfs_get_tree_subvol cleanup path calls btrfs_free_fs_info after super_copy or super_for_commit allocation fails, and btrfs_check_leaked_roots then reads the uninitialized allocated_roots field. Reaching the fault requires local mount access and the allocation-failure condition; the resulting kernel page fault interrupts the host.
Summary
What happened
NULL-pointer dereference in Linux btrfs 6.8 and later affected branches allows local users to crash the kernel during a subvolume mount. The btrfs_get_tree_subvol cleanup path calls btrfs_free_fs_info after super_copy or super_for_commit allocation fails, and btrfs_check_leaked_roots then reads the uninitialized allocated_roots field. Reaching the fault requires local mount access and the allocation-failure condition; the resulting kernel page fault interrupts the host.
The record
- CVE
- CVE-2025-40235
- Published
- Dec 4, 2025
- Updated
- May 11, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- T1499.004
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Dec 4, 2025CVE publishedPublication date reported by the CVE source.
- May 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=3bb17a25bcb09abbd667c6ac86c7c9109ae82bcd <0c2b2d4d053e9840e6da6ed581befa20309f281a
- Affected versionversion=3bb17a25bcb09abbd667c6ac86c7c9109ae82bcd <17679ac6df6c4830ba711835aa8cf961be36cfa1
- Affected versionversion=3bb17a25bcb09abbd667c6ac86c7c9109ae82bcd <b1c2b4e6ffd307720ab6ce42f6749b0c02ba0a73
- Affected versionversion=6.8
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What is affected?
Published CVSS scores
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Attacks
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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