Permission bypass via thread-index allocation race
Published Jul 25, 2026 · Updated Jul 25, 2026
Race condition in Zephyr RTOS before 4.5.0 allows local users to inherit another thread's kernel-object permissions. thread_idx_alloc() reads and clears a free bit in _thread_idx_map[] without lists_lock, so concurrent allocations can assign the same permission index. Exploitation requires user-mode code and CONFIG_USERSPACE, CONFIG_DYNAMIC_OBJECTS, and CONFIG_SMP; the collision aliases kernel-object access-control bits and can leak thread-index entries.
Summary
What happened
Race condition in Zephyr RTOS before 4.5.0 allows local users to inherit another thread's kernel-object permissions. thread_idx_alloc() reads and clears a free bit in _thread_idx_map[] without lists_lock, so concurrent allocations can assign the same permission index. Exploitation requires user-mode code and CONFIG_USERSPACE, CONFIG_DYNAMIC_OBJECTS, and CONFIG_SMP; the collision aliases kernel-object access-control bits and can leak thread-index entries.
The record
- CVE
- CVE-2026-10681
- Published
- Jul 25, 2026
- Updated
- Jul 25, 2026
- Vendor
- Zephyr Project
- Product
- Zephyr RTOS
- Classifications
- CWE-362, T1068
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Jul 25, 2026CVE publishedPublication date reported by the CVE source.
- Jul 25, 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=2.0.0 <4.5.0
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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