CVE-2025-40181
published 2025-11-12CVE-2025-40181: In the Linux kernel, the following vulnerability has been resolved: x86/kvm: Force legacy PCI hole to UC when overriding MTRRs for TDX/SNP When running as an…
PriorityP424medium5.5
EPSS
0.19%
9.4th percentile
In the Linux kernel, the following vulnerability has been resolved:
x86/kvm: Force legacy PCI hole to UC when overriding MTRRs for TDX/SNP
When running as an SNP or TDX guest under KVM, force the legacy PCI hole,
i.e. memory between Top of Lower Usable DRAM and 4GiB, to be mapped as UC
via a forced variable MTRR range.
In most KVM-based setups, legacy devices such as the HPET and TPM are
enumerated via ACPI. ACPI enumeration includes a Memory32Fixed entry, and
optionally a SystemMemory descriptor for an OperationRegion, e.g. if the
device needs to be accessed via a Control Method.
If a SystemMemory entry is present, then the kernel's ACPI driver will
auto-ioremap the region so that it can be accessed at will. However, the
ACPI spec doesn't provide a way to enumerate the memory type of
SystemMemory regions, i.e. there's no way to tell software that a region
must be mapped as UC vs. WB, etc. As a result, Linux's ACPI driver always
maps SystemMemory regions using ioremap_cache(), i.e. as WB on x86.
The dedicated device drivers however, e.g. the HPET driver and TPM driver,
want to map their associated memory as UC or WC, as accessing PCI devices
using WB is unsupported.
On bare metal and non-CoCO, the conflicting requirements "work" as firmware
configures the PCI hole (and other device memory) to be UC in the MTRRs.
So even though the ACPI mappings request WB, they are forced to UC- in the
kernel's tracking due to the kernel properly handling the MTRR overrides,
and thus are compatible with the drivers' requested WC/UC-.
With force WB MTRRs on SNP and TDX guests, the ACPI mappings get their
requested WB if the ACPI mappings are established before the dedicated
driver code attempts to initialize the device. E.g. if acpi_init()
runs before the corresponding device driver is probed, ACPI's WB mapping
will "win", and result in the driver's ioremap() failing because the
existing WB mapping isn't compatible with the requested WC/UC-.
E.g. when a TPM is emulated by the
Affected
12 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| debian | linux | < linux 6.17.6-1 (forky) | linux 6.17.6-1 (forky) |
| linux | linux | — | — |
| linux | linux | >= 8e690b817e38769dc2fa0e7473e5a5dc1fc25795 < 34ff466f74d0fe1db8956f9c245e2bb2c67f67bf | 34ff466f74d0fe1db8956f9c245e2bb2c67f67bf |
| linux | linux | >= 8e690b817e38769dc2fa0e7473e5a5dc1fc25795 < 91ab8a21bda2d2d2842b6159ac060d9100433a3c | 91ab8a21bda2d2d2842b6159ac060d9100433a3c |
| linux | linux | >= 8e690b817e38769dc2fa0e7473e5a5dc1fc25795 < 0dccbc75e18df85399a71933d60b97494110f559 | 0dccbc75e18df85399a71933d60b97494110f559 |
| linux | linux_kernel | >= 0 < 6.12.57-1 | 6.12.57-1 |
| linux | linux_kernel | >= 0 < 6.17.6-1 | 6.17.6-1 |
| linux | linux_kernel | >= 0 < 6.17.0-14.14 | 6.17.0-14.14 |
| linux | linux_kernel | >= 6.12.0 < 6.12.54 | 6.12.54 |
| linux | linux_kernel | >= 6.13.0 < 6.17.4 | 6.17.4 |
| ubuntu | linux-aws | — | — |
| ubuntu | linux-oracle | — | — |
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OSV
linux-azure vulnerabilities
osv·2026-02-24
linux-azure vulnerabilities
linux-azure vulnerabilities
Several security issues were discovered in the Linux kernel.
An attacker could possibly use these to compromise the system.
This update corrects flaws in the following subsystems:
- ARM64 architecture;
- MIPS architecture;
- Nios II architecture;
- PA-RISC architecture;
- RISC-V architecture;
- S390 architecture;
- Sun Sparc architecture;
- x86 architecture;
- Xtensa architecture;
- Block layer subsystem;
- Cryptographic API;
- Compute Acceleration Framework;
- ACPI drivers;
- Drivers core;
- Network block device driver;
- Bluetooth drivers;
- Bus devices;
- Hardware random number generator core;
- Character device driver;
- Clock framework and drivers;
- Data acquisition framework and drivers;
- CPU frequency scaling framework;
- Hardware crypto device drivers
OSV
linux-oem-6.17 vulnerabilities
osv·2026-02-17
linux-oem-6.17 vulnerabilities
linux-oem-6.17 vulnerabilities
Several security issues were discovered in the Linux kernel.
An attacker could possibly use these to compromise the system.
This update corrects flaws in the following subsystems:
- ARM64 architecture;
- MIPS architecture;
- Nios II architecture;
- PA-RISC architecture;
- RISC-V architecture;
- S390 architecture;
- Sun Sparc architecture;
- x86 architecture;
- Xtensa architecture;
- Block layer subsystem;
- Cryptographic API;
- Compute Acceleration Framework;
- ACPI drivers;
- Drivers core;
- Network block device driver;
- Bluetooth drivers;
- Bus devices;
- Hardware random number generator core;
- Character device driver;
- Clock framework and drivers;
- Data acquisition framework and drivers;
- CPU frequency scaling framework;
- Hardware crypto device driv
OSV
linux-aws, linux-oracle vulnerabilities
osv·2026-02-17
linux-aws, linux-oracle vulnerabilities
linux-aws, linux-oracle vulnerabilities
Several security issues were discovered in the Linux kernel.
An attacker could possibly use these to compromise the system.
This update corrects flaws in the following subsystems:
- ARM64 architecture;
- MIPS architecture;
- Nios II architecture;
- PA-RISC architecture;
- RISC-V architecture;
- S390 architecture;
- Sun Sparc architecture;
- x86 architecture;
- Xtensa architecture;
- Block layer subsystem;
- Cryptographic API;
- Compute Acceleration Framework;
- ACPI drivers;
- Drivers core;
- Network block device driver;
- Bluetooth drivers;
- Bus devices;
- Hardware random number generator core;
- Character device driver;
- Clock framework and drivers;
- Data acquisition framework and drivers;
- CPU frequency scaling framework;
- Hardware crypto de
OSV
linux, linux-raspi, linux-realtime vulnerabilities
osv·2026-02-12
linux, linux-raspi, linux-realtime vulnerabilities
linux, linux-raspi, linux-realtime vulnerabilities
Several security issues were discovered in the Linux kernel.
An attacker could possibly use these to compromise the system.
This update corrects flaws in the following subsystems:
- ARM64 architecture;
- MIPS architecture;
- Nios II architecture;
- PA-RISC architecture;
- RISC-V architecture;
- S390 architecture;
- Sun Sparc architecture;
- x86 architecture;
- Xtensa architecture;
- Block layer subsystem;
- Cryptographic API;
- Compute Acceleration Framework;
- ACPI drivers;
- Drivers core;
- Network block device driver;
- Bluetooth drivers;
- Bus devices;
- Hardware random number generator core;
- Character device driver;
- Clock framework and drivers;
- Data acquisition framework and drivers;
- CPU frequency scaling framework;
- Hardwar
GHSA
GHSA-x7gh-c69c-j2v8: In the Linux kernel, the following vulnerability has been resolved:
x86/kvm: Force legacy PCI hole to UC when overriding MTRRs for TDX/SNP
When runn
ghsa_unreviewed·2025-11-13
CVE-2025-40181 GHSA-x7gh-c69c-j2v8: In the Linux kernel, the following vulnerability has been resolved:
x86/kvm: Force legacy PCI hole to UC when overriding MTRRs for TDX/SNP
When runn
In the Linux kernel, the following vulnerability has been resolved:
x86/kvm: Force legacy PCI hole to UC when overriding MTRRs for TDX/SNP
When running as an SNP or TDX guest under KVM, force the legacy PCI hole,
i.e. memory between Top of Lower Usable DRAM and 4GiB, to be mapped as UC
via a forced variable MTRR range.
In most KVM-based setups, legacy devices such as the HPET and TPM are
enumerated via ACPI. ACPI enumeration includes a Memory32Fixed entry, and
optionally a SystemMemory descriptor for an OperationRegion, e.g. if the
device needs to be accessed via a Control Method.
If a SystemMemory entry is present, then the kernel's ACPI driver will
auto-ioremap the region so that it can be accessed at will. However, the
ACPI spec doesn't provide a way to enumerate the memory type of
OSV
x86/kvm: Force legacy PCI hole to UC when overriding MTRRs for TDX/SNP
osv·2025-11-12
CVE-2025-40181 x86/kvm: Force legacy PCI hole to UC when overriding MTRRs for TDX/SNP
x86/kvm: Force legacy PCI hole to UC when overriding MTRRs for TDX/SNP
In the Linux kernel, the following vulnerability has been resolved:
x86/kvm: Force legacy PCI hole to UC when overriding MTRRs for TDX/SNP
When running as an SNP or TDX guest under KVM, force the legacy PCI hole,
i.e. memory between Top of Lower Usable DRAM and 4GiB, to be mapped as UC
via a forced variable MTRR range.
In most KVM-based setups, legacy devices such as the HPET and TPM are
enumerated via ACPI. ACPI enumeration includes a Memory32Fixed entry, and
optionally a SystemMemory descriptor for an OperationRegion, e.g. if the
device needs to be accessed via a Control Method.
If a SystemMemory entry is present, then the kernel's ACPI driver will
auto-ioremap the region so that it can be accessed at will. Howev
OSV
CVE-2025-40181: In the Linux kernel, the following vulnerability has been resolved: x86/kvm: Force legacy PCI hole to UC when overriding MTRRs for TDX/SNP When runnin
osv·2025-11-12
CVE-2025-40181 CVE-2025-40181: In the Linux kernel, the following vulnerability has been resolved: x86/kvm: Force legacy PCI hole to UC when overriding MTRRs for TDX/SNP When runnin
In the Linux kernel, the following vulnerability has been resolved: x86/kvm: Force legacy PCI hole to UC when overriding MTRRs for TDX/SNP When running as an SNP or TDX guest under KVM, force the legacy PCI hole, i.e. memory between Top of Lower Usable DRAM and 4GiB, to be mapped as UC via a forced variable MTRR range. In most KVM-based setups, legacy devices such as the HPET and TPM are enumerated via ACPI. ACPI enumeration includes a Memory32Fixed entry, and optionally a SystemMemory descriptor for an OperationRegion, e.g. if the device needs to be accessed via a Control Method. If a SystemMemory entry is present, then the kernel's ACPI driver will auto-ioremap the region so that it can be accessed at will. However, the ACPI spec doesn't provide a way to enumerate the memory type of Syst
Ubuntu
Linux kernel (Azure) vulnerabilities
vendor_ubuntu·2026-02-24
CVE-2025-40175 Linux kernel (Azure) vulnerabilities
Title: Linux kernel (Azure) vulnerabilities
Summary: Several security issues were fixed in the Linux kernel.
Several security issues were discovered in the Linux kernel.
An attacker could possibly use these to compromise the system.
This update corrects flaws in the following subsystems:
- ARM64 architecture;
- MIPS architecture;
- Nios II architecture;
- PA-RISC architecture;
- RISC-V architecture;
- S390 architecture;
- Sun Sparc architecture;
- x86 architecture;
- Xtensa architecture;
- Block layer subsystem;
- Cryptographic API;
- Compute Acceleration Framework;
- ACPI drivers;
- Drivers core;
- Network block device driver;
- Bluetooth drivers;
- Bus devices;
- Hardware random number generator core;
- Character device driver;
- Clock framework and drivers;
- Data acquisition framewor
Ubuntu
Linux kernel vulnerabilities
vendor_ubuntu·2026-02-17
CVE-2025-40304 Linux kernel vulnerabilities
Title: Linux kernel vulnerabilities
Summary: Several security issues were fixed in the Linux kernel.
Several security issues were discovered in the Linux kernel.
An attacker could possibly use these to compromise the system.
This update corrects flaws in the following subsystems:
- ARM64 architecture;
- MIPS architecture;
- Nios II architecture;
- PA-RISC architecture;
- RISC-V architecture;
- S390 architecture;
- Sun Sparc architecture;
- x86 architecture;
- Xtensa architecture;
- Block layer subsystem;
- Cryptographic API;
- Compute Acceleration Framework;
- ACPI drivers;
- Drivers core;
- Network block device driver;
- Bluetooth drivers;
- Bus devices;
- Hardware random number generator core;
- Character device driver;
- Clock framework and drivers;
- Data acquisition framework and dr
Ubuntu
Linux kernel (OEM) vulnerabilities
vendor_ubuntu·2026-02-17
CVE-2025-68242 Linux kernel (OEM) vulnerabilities
Title: Linux kernel (OEM) vulnerabilities
Summary: Several security issues were fixed in the Linux kernel.
Several security issues were discovered in the Linux kernel.
An attacker could possibly use these to compromise the system.
This update corrects flaws in the following subsystems:
- ARM64 architecture;
- MIPS architecture;
- Nios II architecture;
- PA-RISC architecture;
- RISC-V architecture;
- S390 architecture;
- Sun Sparc architecture;
- x86 architecture;
- Xtensa architecture;
- Block layer subsystem;
- Cryptographic API;
- Compute Acceleration Framework;
- ACPI drivers;
- Drivers core;
- Network block device driver;
- Bluetooth drivers;
- Bus devices;
- Hardware random number generator core;
- Character device driver;
- Clock framework and drivers;
- Data acquisition framework
Ubuntu
Linux kernel vulnerabilities
vendor_ubuntu·2026-02-12
CVE-2025-40304 Linux kernel vulnerabilities
Title: Linux kernel vulnerabilities
Summary: Several security issues were fixed in the Linux kernel.
Several security issues were discovered in the Linux kernel.
An attacker could possibly use these to compromise the system.
This update corrects flaws in the following subsystems:
- ARM64 architecture;
- MIPS architecture;
- Nios II architecture;
- PA-RISC architecture;
- RISC-V architecture;
- S390 architecture;
- Sun Sparc architecture;
- x86 architecture;
- Xtensa architecture;
- Block layer subsystem;
- Cryptographic API;
- Compute Acceleration Framework;
- ACPI drivers;
- Drivers core;
- Network block device driver;
- Bluetooth drivers;
- Bus devices;
- Hardware random number generator core;
- Character device driver;
- Clock framework and drivers;
- Data acquisition framework and dr
Red Hat
kernel: x86/kvm: Force legacy PCI hole to UC when overriding MTRRs for TDX/SNP
vendor_redhat·2025-11-12·CVSS 5.5
CVE-2025-40181 [MEDIUM] kernel: x86/kvm: Force legacy PCI hole to UC when overriding MTRRs for TDX/SNP
kernel: x86/kvm: Force legacy PCI hole to UC when overriding MTRRs for TDX/SNP
In the Linux kernel, the following vulnerability has been resolved:
x86/kvm: Force legacy PCI hole to UC when overriding MTRRs for TDX/SNP
When running as an SNP or TDX guest under KVM, force the legacy PCI hole,
i.e. memory between Top of Lower Usable DRAM and 4GiB, to be mapped as UC
via a forced variable MTRR range.
In most KVM-based setups, legacy devices such as the HPET and TPM are
enumerated via ACPI. ACPI enumeration includes a Memory32Fixed entry, and
optionally a SystemMemory descriptor for an OperationRegion, e.g. if the
device needs to be accessed via a Control Method.
If a SystemMemory entry is present, then the kernel's ACPI driver will
auto-ioremap the region so that it can be accessed at will. H
Debian
CVE-2025-40181: linux - In the Linux kernel, the following vulnerability has been resolved: x86/kvm: Fo...
vendor_debian·2025
CVE-2025-40181 [LOW] CVE-2025-40181: linux - In the Linux kernel, the following vulnerability has been resolved: x86/kvm: Fo...
In the Linux kernel, the following vulnerability has been resolved: x86/kvm: Force legacy PCI hole to UC when overriding MTRRs for TDX/SNP When running as an SNP or TDX guest under KVM, force the legacy PCI hole, i.e. memory between Top of Lower Usable DRAM and 4GiB, to be mapped as UC via a forced variable MTRR range. In most KVM-based setups, legacy devices such as the HPET and TPM are enumerated via ACPI. ACPI enumeration includes a Memory32Fixed entry, and optionally a SystemMemory descriptor for an OperationRegion, e.g. if the device needs to be accessed via a Control Method. If a SystemMemory entry is present, then the kernel's ACPI driver will auto-ioremap the region so that it can be accessed at will. However, the ACPI spec doesn't provide a way to enumerate the memory type of Syst
No detection rules found.
No public exploits indexed.
2025-11-12
Published