Write failure via async DIO iterator misrouting
Published Jan 19, 2025 · Updated May 11, 2026
Denial of service in Linux kernel netfs 6.8 through 6.13-rc6 allows local users to fail asynchronous direct writes. netfs_unbuffered_write_iter_locked misclassifies kernel-initiated asynchronous DIO as a userspace write, sending a bio_vec iterator to netfs_extract_user_iter, which accepts only IOVEC and UBUF. Triggering it requires a CIFS-mounted file used by a direct-I/O loop device; the kernel logs a warning and rejects the write without reported data disclosure or code execution.
Summary
What happened
Denial of service in Linux kernel netfs 6.8 through 6.13-rc6 allows local users to fail asynchronous direct writes. netfs_unbuffered_write_iter_locked misclassifies kernel-initiated asynchronous DIO as a userspace write, sending a bio_vec iterator to netfs_extract_user_iter, which accepts only IOVEC and UBUF. Triggering it requires a CIFS-mounted file used by a direct-I/O loop device; the kernel logs a warning and rejects the write without reported data disclosure or code execution.
The record
- CVE
- CVE-2025-21643
- Published
- Jan 19, 2025
- Updated
- May 11, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- T1499
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Jan 19, 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?
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- Affected versionversion=153a9961b551101cd38e94e26cd92fbfd198b19b <3f6bc9e3ab9b127171d39f9ac6eca1abb693b731
- Affected versionversion=153a9961b551101cd38e94e26cd92fbfd198b19b <9f3a265836844eda30bf34c2584b8011fd4f0f49
- Affected versionversion=6.8
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
- Upstream async-DIO trigger sequenceproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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