Guest-to-host memory writes via writable VNCR mapping
Published Aug 15, 2026 · Updated Aug 15, 2026
Incorrect permission assignment in Linux KVM allows guest OS users to write read-only VNCR backing pages on affected arm64 hosts. KVM maps an L1 Virtual Nested Control Register into the host stage-1 fixmap using guest stage-1 permissions without constraining the mapping to a read-only backing PFN. Guest OS users must control an L1 nested-hypervisor guest; writes bypass the read-only memslot boundary, and repeated faults leak page references until host memory is exhausted.
Summary
What happened
Incorrect permission assignment in Linux KVM allows guest OS users to write read-only VNCR backing pages on affected arm64 hosts. KVM maps an L1 Virtual Nested Control Register into the host stage-1 fixmap using guest stage-1 permissions without constraining the mapping to a read-only backing PFN. Guest OS users must control an L1 nested-hypervisor guest; writes bypass the read-only memslot boundary, and repeated faults leak page references until host memory is exhausted.
The record
- CVE
- CVE-2026-72279
- Published
- Aug 15, 2026
- Updated
- Aug 15, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- CWE-279, T1068, T1499.004
- Attack vector
- local
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 15, 2026CVE publishedPublication date reported by the CVE source.
- Aug 15, 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=2a359e072596fcb2e9e85017a865e3618a2fe5b5 <2684e02bac41c5220f6c1ab2bdcc957b71812977
- Affected versionversion=2a359e072596fcb2e9e85017a865e3618a2fe5b5 <5c50db5bcbb9073cb2fd97be51b962de92f429e9
- Affected versionversion=2a359e072596fcb2e9e85017a865e3618a2fe5b5 <d35defbdfcb15296ebe28968ad7452c1a8c11cea
- Affected versionversion=6.16
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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