System hang via single-CPU freelist fallback loop
Published Sep 16, 2026 · Updated Sep 16, 2026
Denial of service in the Linux kernel allows attackers to hang the system through BPF per-CPU freelist lock re-entry. __pcpu_freelist_push() skips the current CPU after recursive locking returns -EDEADLK, then loops without attempting any head when no other possible CPU exists. Reachability requires an NMI to re-enter the BPF freelist push while interrupted code holds its only per-CPU lock on a uniprocessor or kernel limited to one possible CPU; the reported impact is an infinite hang.
Summary
What happened
Denial of service in the Linux kernel allows attackers to hang the system through BPF per-CPU freelist lock re-entry. __pcpu_freelist_push() skips the current CPU after recursive locking returns -EDEADLK, then loops without attempting any head when no other possible CPU exists. Reachability requires an NMI to re-enter the BPF freelist push while interrupted code holds its only per-CPU lock on a uniprocessor or kernel limited to one possible CPU; the reported impact is an infinite hang.
The record
- CVE
- CVE-2026-89991
- Published
- Sep 16, 2026
- Updated
- Sep 16, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- T1499
- Attack vector
- local
- Privileges
- Unavailable
Timeline
How it unfolded
- Sep 16, 2026CVE publishedPublication date reported by the CVE source.
- Sep 16, 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=6.15
- Affected versionversion=f2ac0e5d1c4dcc55d6510dcaefb8f45661a9a1fb <a24a146ae2cb5d9faeea96d10010fcb6579abe1f
- Affected versionversion=f2ac0e5d1c4dcc55d6510dcaefb8f45661a9a1fb <a5b5e62baceff9e252c6535cf42a027d04f226cf
- Affected versionversion=f2ac0e5d1c4dcc55d6510dcaefb8f45661a9a1fb <efebf6496685c93150df5bb0794363ae70c5f58a
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
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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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