Host interruption via concurrent VNCR unmapping
Published Sep 16, 2026 · Updated Sep 16, 2026
Race condition in Linux 6.16 KVM on arm64 allows attackers to trigger a kernel BUG through concurrent VNCR unmapping. The TLB-invalidation path checks vncr_tlb::cpu before unmapping, while vcpu_put() can concurrently reset and unmap the same VNCR, creating a TOCTOU race that reaches BUG_ON() or vncr_fixmap(-1). Reachability requires arm64 KVM nested virtualization and concurrent VNCR teardown activity; the published material does not identify attacker privileges.
Summary
What happened
Race condition in Linux 6.16 KVM on arm64 allows attackers to trigger a kernel BUG through concurrent VNCR unmapping. The TLB-invalidation path checks vncr_tlb::cpu before unmapping, while vcpu_put() can concurrently reset and unmap the same VNCR, creating a TOCTOU race that reaches BUG_ON() or vncr_fixmap(-1). Reachability requires arm64 KVM nested virtualization and concurrent VNCR teardown activity; the published material does not identify attacker privileges.
The record
- CVE
- CVE-2026-89917
- Published
- Sep 16, 2026
- Updated
- Sep 16, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- Unavailable
- Attack vector
- Unavailable
- 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?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=6.16
- Affected versionversion=7270cc9157f474dfc46750a34c9d7defc686b2eb <38640bc32be3fcf9526d477155bc19d3f146231f
- Affected versionversion=7270cc9157f474dfc46750a34c9d7defc686b2eb <5cbd8761d001c11ada73b1753d772c4745a70e72
- Affected versionversion=7270cc9157f474dfc46750a34c9d7defc686b2eb <9065c1261f8a05c6a7a2d90048c7c0665ab2896d
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
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Public exploit references
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Technologies
Your stack
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Your stack
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