Kernel warning via stale Btrfs device lookup
Published Jun 19, 2024 · Updated May 23, 2026
A race condition in Linux kernel Btrfs 5.9 through 5.15.10 allows local users to trigger a kernel warning through mount metadata reads. During btrfs_prepare_sprout, devices move to seed_list while btrfs_show_devname searches the old list and fails to find a device instead of using latest_dev. Local low-privileged access, a Btrfs seed-device conversion, and race timing are required; the published test reaches a warning rather than a demonstrated crash.
Summary
What happened
A race condition in Linux kernel Btrfs 5.9 through 5.15.10 allows local users to trigger a kernel warning through mount metadata reads. During btrfs_prepare_sprout, devices move to seed_list while btrfs_show_devname searches the old list and fails to find a device instead of using latest_dev. Local low-privileged access, a Btrfs seed-device conversion, and race timing are required; the published test reaches a warning rather than a demonstrated crash.
The record
- CVE
- CVE-2021-47599
- Published
- Jun 19, 2024
- Updated
- May 23, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- T1499
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Jun 19, 2024CVE publishedPublication date reported by the CVE source.
- May 23, 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=1c986b7e8c1bf8fabbc294036b003286cc3a8c7e
- Affected versionversion=3d3452920cacc3a46444ecca26af5d181410ff19
- Affected versionversion=4.19.141 <4.20
- Affected versionversion=4faf55b03823e96c44dc4e364520000ed3b12fdb <6605fd2f394bba0a0059df2b6cfc87b0b6d393a2
- Affected versionversion=4faf55b03823e96c44dc4e364520000ed3b12fdb <e342c2558016ead462f376b6c6c2ac5efc17f3b1
- Affected versionversion=5.4.60 <5.5
- Affected versionversion=5.7.17 <5.8
- Affected versionversion=5.8.3 <5.9
- Affected versionversion=5.9
- Affected versionversion=ca21728e18d34fd5f449bb0581160e0eaee498a6
- Affected versionversion=fa511954694cbea4d0cb59c81c8670276920c08c
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
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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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