Local kernel crash via mismatched COW crypto context
Published Jul 19, 2026 · Updated Jul 19, 2026
NULL pointer dereference in Linux Kernel 6.4 through 7.1.2 allows local users to crash the system during an F2FS atomic write. f2fs_write_begin() builds the read bio with the COW inode, so f2fs_grab_read_bio() selects decryption from that inode while the folio uses the original inode. The path requires an encrypted COW inode for an unencrypted original file; dereferencing the original inode's null i_crypt_info crashes the kernel.
Summary
What happened
NULL pointer dereference in Linux Kernel 6.4 through 7.1.2 allows local users to crash the system during an F2FS atomic write. f2fs_write_begin() builds the read bio with the COW inode, so f2fs_grab_read_bio() selects decryption from that inode while the folio uses the original inode. The path requires an encrypted COW inode for an unencrypted original file; dereferencing the original inode's null i_crypt_info crashes the kernel.
The record
- CVE
- CVE-2026-63811
- Published
- Jul 19, 2026
- Updated
- Jul 19, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux Kernel
- Classifications
- CWE-476, T1499
- Attack vector
- local
- Privileges
- Unavailable
Timeline
How it unfolded
- Jul 19, 2026CVE publishedPublication date reported by the CVE source.
- Jul 19, 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?
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- Affected versionversion=591fc34e1f98b0d7eef4aa3440bfdff3c5a1cadd <a41075acde0124d2f8a5f563068a5d63e8ffd57b
- Affected versionversion=591fc34e1f98b0d7eef4aa3440bfdff3c5a1cadd <a92332f32a8d31a7eee47b1dc1d751cb3319908f
- Affected versionversion=6.4
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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Public exploit references
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Technologies
Your stack
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Your stack
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