System hard lock via recursive kernel locking
Published Sep 23, 2025 · Updated Sep 23, 2025
Denial of service in the Linux kernel BPF timer path allows local users to hard-lock the system through a crafted sched_ext BPF program. In __bpf_async_init(), an atomic allocation can make memory-cgroup event handling acquire a scheduler or cgroup lock already held by the calling path. Reachability requires permission to load the BPF scheduler program and memory-cgroup pressure sufficient to raise an event; the resulting deadlock stops the system.
Summary
What happened
Denial of service in the Linux kernel BPF timer path allows local users to hard-lock the system through a crafted sched_ext BPF program. In __bpf_async_init(), an atomic allocation can make memory-cgroup event handling acquire a scheduler or cgroup lock already held by the calling path. Reachability requires permission to load the BPF scheduler program and memory-cgroup pressure sufficient to raise an event; the resulting deadlock stops the system.
The record
- CVE
- CVE-2025-39886
- Published
- Sep 23, 2025
- Updated
- Sep 23, 2025
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- T1499
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Sep 23, 2025CVE publishedPublication date reported by the CVE source.
- Sep 23, 2025Record 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=5.15
- Affected versionversion=b00628b1c7d595ae5b544e059c27b1f5828314b4 <449682e76f32601f211816d3e2100bed87e67a4c
- Affected versionversion=b00628b1c7d595ae5b544e059c27b1f5828314b4 <6d78b4473cdb08b74662355a9e8510bde09c511e
- Affected versionversion=b00628b1c7d595ae5b544e059c27b1f5828314b4 <ac70cd446f83ccb25532b343919ab86eacdcd06a
- Affected versionversion=b00628b1c7d595ae5b544e059c27b1f5828314b4 <cd1fd26bb13473c1734e3026b2b97025a0a4087b
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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