Kernel code execution via PI futex race
Published Jan 29, 2021 · Updated Feb 25, 2026
Use-after-free in Linux kernel PI futex fault handling through 5.10.11 allows local users to execute code in the kernel. The fault path leaves kernel and user-space PI-futex state inconsistent when the user-space futex word is not writable, enabling later operations to use a freed task kernel stack. An unprivileged local account must manipulate the futex mapping during fault handling; successful exploitation gains kernel-level execution, while failure can crash the system.
Summary
What happened
Use-after-free in Linux kernel PI futex fault handling through 5.10.11 allows local users to execute code in the kernel. The fault path leaves kernel and user-space PI-futex state inconsistent when the user-space futex word is not writable, enabling later operations to use a freed task kernel stack. An unprivileged local account must manipulate the futex mapping during fault handling; successful exploitation gains kernel-level execution, while failure can crash the system.
The record
- CVE
- CVE-2021-3347
- Published
- Jan 29, 2021
- Updated
- Feb 25, 2026
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-416, T1068
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Jan 29, 2021CVE publishedPublication date reported by the CVE source.
- Feb 25, 2026Record updatedLatest update available in the CVE record.
Exploitability
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What is affected?
Affected products and versions are unavailable in this record.
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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