Local service interruption via preemptible estimator timer
Published Oct 1, 2025 · Updated May 11, 2026
Race condition in Linux 6.12 through 6.12.45, 6.13 through 6.16.5, and 6.17-rc1 through 6.17-rc4 allows local users to interrupt service. In net/core/gen_estimator.c, est_timer begins a seqcount write and updates estimator rates while PREEMPT_RT can preempt the timer callback, violating the write-side non-preemptibility requirement. A local low-privileged user and a kernel built with CONFIG_PREEMPT_RT=y are required; the published impact is limited to availability, with no confidentiality or integrity impact.
Summary
What happened
Race condition in Linux 6.12 through 6.12.45, 6.13 through 6.16.5, and 6.17-rc1 through 6.17-rc4 allows local users to interrupt service. In net/core/gen_estimator.c, est_timer begins a seqcount write and updates estimator rates while PREEMPT_RT can preempt the timer callback, violating the write-side non-preemptibility requirement. A local low-privileged user and a kernel built with CONFIG_PREEMPT_RT=y are required; the published impact is limited to availability, with no confidentiality or integrity impact.
The record
- CVE
- CVE-2025-39900
- Published
- Oct 1, 2025
- Updated
- May 11, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- T1499
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Oct 1, 2025CVE publishedPublication date reported by the CVE source.
- May 11, 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=6.12
- Affected versionversion=d2d6422f8bd17c6bb205133e290625a564194496 <9f74c0ea9b26d1505d55b61e36b1623dd347e1d1
- Affected versionversion=d2d6422f8bd17c6bb205133e290625a564194496 <a22ec2ee824be30803068a52f78f7ffe3bc879fb
- Affected versionversion=d2d6422f8bd17c6bb205133e290625a564194496 <e79923824c48b930609680be04cb29253fc4a17d
What conditions does exploitation require?
What is affected?
Published CVSS scores
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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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