Reader hang via unsubmitted pending read bio
Published Jul 19, 2026 · Updated Jul 19, 2026
Denial of service in Linux kernel f2fs 7.0 allows attackers to hang readers indefinitely through a large-folio read error. In f2fs_read_data_large_folio(), an error on a later folio returns before submitting the pending read bio for earlier folios, leaving them locked without completion. Triggering requires the large-folio readahead path on an f2fs filesystem and a later folio error before any of that folio's blocks enter the bio; affected readers then wait indefinitely.
Summary
What happened
Denial of service in Linux kernel f2fs 7.0 allows attackers to hang readers indefinitely through a large-folio read error. In f2fs_read_data_large_folio(), an error on a later folio returns before submitting the pending read bio for earlier folios, leaving them locked without completion. Triggering requires the large-folio readahead path on an f2fs filesystem and a later folio error before any of that folio's blocks enter the bio; affected readers then wait indefinitely.
The record
- CVE
- CVE-2026-63820
- Published
- Jul 19, 2026
- Updated
- Jul 19, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux Kernel
- Classifications
- CWE-833, T1499.004
- Attack vector
- Unavailable
- 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?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=7.0
- Affected versionversion=a5d8b9d94e1863f3ebb7182c238b2c713f6f4efd <48c92559e7b66fdc3cbc74f6e152e66ec0150a0a
- Affected versionversion=a5d8b9d94e1863f3ebb7182c238b2c713f6f4efd <74c8d2ec95c59a5651ecd975c466998af1961fd4
What conditions does exploitation require?
What is affected?
Published CVSS scores
No CVSS assessment is available in this record.
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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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