Device unavailability via conflicting ACPI memory mappings
Published Nov 12, 2025 · Updated May 11, 2026
Denial of service in Linux kernel KVM allows local users to prevent TPM or HPET drivers from loading in SNP or TDX guests. ACPI maps a SystemMemory region as write-back before the device probe, so the later write-combining or uncacheable ioremap request conflicts and fails. The failure requires an x86 KVM confidential guest with forced-WB MTRRs, an ACPI SystemMemory region, and ACPI initialization before the dedicated driver probe.
Summary
What happened
Denial of service in Linux kernel KVM allows local users to prevent TPM or HPET drivers from loading in SNP or TDX guests. ACPI maps a SystemMemory region as write-back before the device probe, so the later write-combining or uncacheable ioremap request conflicts and fails. The failure requires an x86 KVM confidential guest with forced-WB MTRRs, an ACPI SystemMemory region, and ACPI initialization before the dedicated driver probe.
The record
- CVE
- CVE-2025-40181
- Published
- Nov 12, 2025
- Updated
- May 11, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- Unavailable
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Nov 12, 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=8e690b817e38769dc2fa0e7473e5a5dc1fc25795 <0dccbc75e18df85399a71933d60b97494110f559
- Affected versionversion=8e690b817e38769dc2fa0e7473e5a5dc1fc25795 <34ff466f74d0fe1db8956f9c245e2bb2c67f67bf
- Affected versionversion=8e690b817e38769dc2fa0e7473e5a5dc1fc25795 <91ab8a21bda2d2d2842b6159ac060d9100433a3c
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
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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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