Evidence used
- No CISA KEV confirmation is currently recorded.
- EPSS is 0.20% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2025
CVE-2025-40181High confidence
x86/kvm: Force legacy PCI hole to UC when overriding MTRRs for TDX/SNP
Linux · Linux
…UnscoredAssess manually
Patch only the product branches with a verified fix
Fix availability varies by productNo CVSS base score is available from the CNA, CISA ADP or NIST. Absence of a score is not evidence of low risk; review the vendor advisory, affected exposure and exploit evidence. Verified remediation exists for at least one product or source, but 211 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityUnscored→Operational priority:Needs assessment, manual assessment needed.unscored
Compensating controls
- Validate the affected product branch and deploy the verified fixed release.
- Restrict local access and enforce least privilege on affected hosts.
- Monitor vendor guidance and exploitation sources for a material change.
Verification
- Confirm that the asset runs Linux Linux and falls inside the recorded affected range.
- Verify the installed build against the product-specific fixed version after deployment.
- Validate exposure, authentication requirements and compensating controls in the actual environment.
- Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Remediation availability differs by product scope
Verified remediation exists for at least one product or source, but 211 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
- Red Hat Product Security: 198 affected or under-investigation product states without a fixed product state in the same current advisory
- Canonical Ubuntu Security: 13 affected package states with no published fix
Distribution package intelligence
17 package statesRelease-specific package status
Debian, ubuntu findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.
Package result overrides the generic status
BlackTree has verified remediation for at least one product or source, but the relevant distribution still reports no fixed package for 13 affected package states shown here. Treat those rows as affected with no fix until that distribution publishes a fixed version.
Repository candidate not checked
A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.
| Distribution release | Source package | Vendor state | Fixed version | Evidence |
|---|---|---|---|---|
| Debian trixietrixie · source | linux | Vendor fix publishedDebian records a fixed source-package version for this release. | 6.12.57-1 | Debian Security Tracker ↗Source updated 6 Oct 2026 |
| Debian bookwormbookworm · source | linux | Not affectedDebian marks this release not affected (fixed-version marker 0). | Not published in this feed | Debian Security Tracker ↗Source updated 6 Oct 2026 |
| Debian forkyforky · source | linux | Vendor fix publishedDebian records a fixed source-package version for this release. | 6.17.6-1 | Debian Security Tracker ↗Source updated 6 Oct 2026 |
| Debian sidsid · source | linux | Vendor fix publishedDebian records a fixed source-package version for this release. | 6.17.6-1 | Debian Security Tracker ↗Source updated 6 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-aws-6.14 | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-azure-6.11 | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-azure-fde-6.14 | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-azure-nvidia-6.14 | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-gcp-6.11 | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-hwe-6.11 | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-lowlatency-hwe-6.11 | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-nvidia-6.17 | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-oem-6.11 | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-oracle-6.14 | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-raspi-realtime | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-realtime | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | linux-riscv | Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
Direct vendor intelligence
2 currentAuthoritative vendor CSAF and VEX advisories
Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.
CVE-2025-40181 · CSAF 2.0 · revision 37 · interimSUSE Product Security TeamCVE-2025-40181
The vendor explicitly identifies these products as affected by this CVE.
- SUSE Linux Micro Extras 6.2:kernel-obs-build
- SUSE Linux Micro Extras 6.2:kernel-syms
- SLES 15 SP1 CHOST Images for Amazon EC2
- SLES 15 SP2 CHOST Images for Amazon EC2
- SLES 15 SP3 CHOST Images for Amazon EC2
- SLES 15 SP4 CHOST Images for Amazon EC2
- SLES 15 SP5 CHOST Images for Amazon EC2
- SLES 15 SP1 CHOST Images for Google
- SLES 15 SP2 CHOST Images for Google
- SLES 15 SP3 CHOST Images for Google
- SLES 15 SP4 CHOST Images for Google
- SLES 15 SP5 CHOST Images for Google
- Summary
- 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 hypervisor (ignoring the security implications of relying on what is allegedly an untrusted entity to store measurements), the TPM driver will request UC and fail: [ 1.730459] ioremap error for 0xfed40000-0xfed45000, requested 0x2, got 0x0 [ 1.732780] tpm_tis MSFT0101:00: probe with driver tpm_tis failed with error -12 Note, the '0x2' and '0x0' values refer to "enum page_cache_mode", not x86's memtypes (which frustratingly are an almost pure inversion; 2 == WB, 0 == UC). E.g. tracing mapping requests for TPM TIS yields: Mapping TPM TIS with req_type = 0 WARNING: CPU: 22 PID: 1 at arch/x86/mm/pat/memtype.c:530 memtype_reserve+0x2ab/0x460 Modules linked in: CPU: 22 UID: 0 PID: 1 Comm: swapper/0 Tainted: G W 6.16.0-rc7+ #2 VOLUNTARY Tainted: [W]=WARN Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/29/2025 RIP: 0010:memtype_reserve+0x2ab/0x460 __ioremap_caller+0x16d/0x3d0 ioremap_cache+0x17/0x30 x86_acpi_os_ioremap+0xe/0x20 acpi_os_map_iomem+0x1f3/0x240 acpi_os_map_memory+0xe/0x20 acpi_ex_system_memory_space_handler+0x273/0x440 acpi_ev_address_space_dispatch+0x176/0x4c0 acpi_ex_access_region+0x2ad/0x530 acpi_ex_field_datum_io+0xa2/0x4f0 acpi_ex_extract_from_field+0x296/0x3e0 acpi_ex_read_data_from_field+0xd1/0x460 acpi_ex_resolve_node_to_value+0x2ee/0x530 acpi_ex_resolve_to_value+0x1f2/0x540 acpi_ds_evaluate_name_path+0x11b/0x190 acpi_ds_exec_end_op+0x456/0x960 acpi_ps_parse_loop+0x27a/0xa50 acpi_ps_parse_aml+0x226/0x600 acpi_ps_execute_method+0x172/0x3e0 acpi_ns_evaluate+0x175/0x5f0 acpi_evaluate_object+0x213/0x490 acpi_evaluate_integer+0x6d/0x140 acpi_bus_get_status+0x93/0x150 acpi_add_single_object+0x43a/0x7c0 acpi_bus_check_add+0x149/0x3a0 acpi_bus_check_add_1+0x16/0x30 acpi_ns_walk_namespace+0x22c/0x360 acpi_walk_namespace+0x15c/0x170 acpi_bus_scan+0x1dd/0x200 acpi_scan_init+0xe5/0x2b0 acpi_init+0x264/0x5b0 do_one_i ---truncated---
- Remediation
- To install this SUSE Security Update use the SUSE recommended installation methods like YaST online_update or "zypper patch".
CVE-2025-40181 · CSAF 2.0 · revision 3 · finalRed Hat Product Securitykernel: x86/kvm: Force legacy PCI hole to UC when overriding MTRRs for TDX/SNP
The vendor explicitly identifies these products as affected by this CVE.
- kernel as a component of Red Hat Enterprise Linux 10
- kernel-64k as a component of Red Hat Enterprise Linux 10
- kernel-64k-core as a component of Red Hat Enterprise Linux 10
- kernel-64k-debug as a component of Red Hat Enterprise Linux 10
- kernel-64k-debug-core as a component of Red Hat Enterprise Linux 10
- kernel-64k-debug-devel as a component of Red Hat Enterprise Linux 10
- kernel-64k-debug-devel-matched as a component of Red Hat Enterprise Linux 10
- kernel-64k-debug-modules as a component of Red Hat Enterprise Linux 10
- kernel-64k-debug-modules-core as a component of Red Hat Enterprise Linux 10
- kernel-64k-debug-modules-extra as a component of Red Hat Enterprise Linux 10
- kernel-64k-devel as a component of Red Hat Enterprise Linux 10
- kernel-64k-devel-matched as a component of Red Hat Enterprise Linux 10
- Summary
- 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 hypervisor (ignoring the security implications of relying on what is allegedly an untrusted entity to store measurements), the TPM driver will request UC and fail: [ 1.730459] ioremap error for 0xfed40000-0xfed45000, requested 0x2, got 0x0 [ 1.732780] tpm_tis MSFT0101:00: probe with driver tpm_tis failed with error -12 Note, the '0x2' and '0x0' values refer to "enum page_cache_mode", not x86's memtypes (which frustratingly are an almost pure inversion; 2 == WB, 0 == UC). E.g. tracing mapping requests for TPM TIS yields: Mapping TPM TIS with req_type = 0 WARNING: CPU: 22 PID: 1 at arch/x86/mm/pat/memtype.c:530 memtype_reserve+0x2ab/0x460 Modules linked in: CPU: 22 UID: 0 PID: 1 Comm: swapper/0 Tainted: G W 6.16.0-rc7+ #2 VOLUNTARY Tainted: [W]=WARN Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/29/2025 RIP: 0010:memtype_reserve+0x2ab/0x460 __ioremap_caller+0x16d/0x3d0 ioremap_cache+0x17/0x30 x86_acpi_os_ioremap+0xe/0x20 acpi_os_map_iomem+0x1f3/0x240 acpi_os_map_memory+0xe/0x20 acpi_ex_system_memory_space_handler+0x273/0x440 acpi_ev_address_space_dispatch+0x176/0x4c0 acpi_ex_access_region+0x2ad/0x530 acpi_ex_field_datum_io+0xa2/0x4f0 acpi_ex_extract_from_field+0x296/0x3e0 acpi_ex_read_data_from_field+0xd1/0x460 acpi_ex_resolve_node_to_value+0x2ee/0x530 acpi_ex_resolve_to_value+0x1f2/0x540 acpi_ds_evaluate_name_path+0x11b/0x190 acpi_ds_exec_end_op+0x456/0x960 acpi_ps_parse_loop+0x27a/0xa50 acpi_ps_parse_aml+0x226/0x600 acpi_ps_execute_method+0x172/0x3e0 acpi_ns_evaluate+0x175/0x5f0 acpi_evaluate_object+0x213/0x490 acpi_evaluate_integer+0x6d/0x140 acpi_bus_get_status+0x93/0x150 acpi_add_single_object+0x43a/0x7c0 acpi_bus_check_add+0x149/0x3a0 acpi_bus_check_add_1+0x16/0x30 acpi_ns_walk_namespace+0x22c/0x360 acpi_walk_namespace+0x15c/0x170 acpi_bus_scan+0x1dd/0x200 acpi_scan_init+0xe5/0x2b0 acpi_init+0x264/0x5b0 do_one_i ---truncated---
- Remediation
- Fix deferred
No CVSS base score is available from the CNA, CISA ADP or NIST. Absence of a score is not evidence of low risk; review the vendor advisory, affected exposure and exploit evidence. Verified remediation exists for at least one product or source, but 211 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
Fix availability varies by product01
What, why and how
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 hypervisor (ignoring the security implications of relying on what is allegedly an untrusted entity to store measurements), the TPM driver will request UC and fail: [ 1.730459] ioremap error for 0xfed40000-0xfed45000, requested 0x2, got 0x0 [ 1.732780] tpm_tis MSFT0101:00: probe with driver tpm_tis failed with error -12 Note, the '0x2' and '0x0' values refer to "enum page_cache_mode", not x86's memtypes (which frustratingly are an almost pure inversion; 2 == WB, 0 == UC). E.g. tracing mapping requests for TPM TIS yields: Mapping TPM TIS with req_type = 0 WARNING: CPU: 22 PID: 1 at arch/x86/mm/pat/memtype.c:530 memtype_reserve+0x2ab/0x460 Modules linked in: CPU: 22 UID: 0 PID: 1 Comm: swapper/0 Tainted: G W 6.16.0-rc7+ #2 VOLUNTARY Tainted: [W]=WARN Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/29/2025 RIP: 0010:memtype_reserve+0x2ab/0x460 __ioremap_caller+0x16d/0x3d0 ioremap_cache+0x17/0x30 x86_acpi_os_ioremap+0xe/0x20 acpi_os_map_iomem+0x1f3/0x240 acpi_os_map_memory+0xe/0x20 acpi_ex_system_memory_space_handler+0x273/0x440 acpi_ev_address_space_dispatch+0x176/0x4c0 acpi_ex_access_region+0x2ad/0x530 acpi_ex_field_datum_io+0xa2/0x4f0 acpi_ex_extract_from_field+0x296/0x3e0 acpi_ex_read_data_from_field+0xd1/0x460 acpi_ex_resolve_node_to_value+0x2ee/0x530 acpi_ex_resolve_to_value+0x1f2/0x540 acpi_ds_evaluate_name_path+0x11b/0x190 acpi_ds_exec_end_op+0x456/0x960 acpi_ps_parse_loop+0x27a/0xa50 acpi_ps_parse_aml+0x226/0x600 acpi_ps_execute_method+0x172/0x3e0 acpi_ns_evaluate+0x175/0x5f0 acpi_evaluate_object+0x213/0x490 acpi_evaluate_integer+0x6d/0x140 acpi_bus_get_status+0x93/0x150 acpi_add_single_object+0x43a/0x7c0 acpi_bus_check_add+0x149/0x3a0 acpi_bus_check_add_1+0x16/0x30 acpi_ns_walk_namespace+0x22c/0x360 acpi_walk_namespace+0x15c/0x170 acpi_bus_scan+0x1dd/0x200 acpi_scan_init+0xe5/0x2b0 acpi_init+0x264/0x5b0 do_one_i ---truncated---
What
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 hypervisor (ignoring the security implications of relying on what is allegedly an untrusted entity to store measurements), the TPM driver will request UC and fail: [ 1.730459] ioremap error for 0xfed40000-0xfed45000, requested 0x2, got 0x0 [ 1.732780] tpm_tis MSFT0101:00: probe with driver tpm_tis failed with error -12 Note, the '0x2' and '0x0' values refer to "enum page_cache_mode", not x86's memtypes (which frustratingly are an almost pure inversion; 2 == WB, 0 == UC). E.g. tracing mapping requests for TPM TIS yields: Mapping TPM TIS with req_type = 0 WARNING: CPU: 22 PID: 1 at arch/x86/mm/pat/memtype.c:530 memtype_reserve+0x2ab/0x460 Modules linked in: CPU: 22 UID: 0 PID: 1 Comm: swapper/0 Tainted: G W 6.16.0-rc7+ #2 VOLUNTARY Tainted: [W]=WARN Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/29/2025 RIP: 0010:memtype_reserve+0x2ab/0x460 __ioremap_caller+0x16d/0x3d0 ioremap_cache+0x17/0x30 x86_acpi_os_ioremap+0xe/0x20 acpi_os_map_iomem+0x1f3/0x240 acpi_os_map_memory+0xe/0x20 acpi_ex_system_memory_space_handler+0x273/0x440 acpi_ev_address_space_dispatch+0x176/0x4c0 acpi_ex_access_region+0x2ad/0x530 acpi_ex_field_datum_io+0xa2/0x4f0 acpi_ex_extract_from_field+0x296/0x3e0 acpi_ex_read_data_from_field+0xd1/0x460 acpi_ex_resolve_node_to_value+0x2ee/0x530 acpi_ex_resolve_to_value+0x1f2/0x540 acpi_ds_evaluate_name_path+0x11b/0x190 acpi_ds_exec_end_op+0x456/0x960 acpi_ps_parse_loop+0x27a/0xa50 acpi_ps_parse_aml+0x226/0x600 acpi_ps_execute_method+0x172/0x3e0 acpi_ns_evaluate+0x175/0x5f0 acpi_evaluate_object+0x213/0x490 acpi_evaluate_integer+0x6d/0x140 acpi_bus_get_status+0x93/0x150 acpi_add_single_object+0x43a/0x7c0 acpi_bus_check_add+0x149/0x3a0 acpi_bus_check_add_1+0x16/0x30 acpi_ns_walk_namespace+0x22c/0x360 acpi_walk_namespace+0x15c/0x170 acpi_bus_scan+0x1dd/0x200 acpi_scan_init+0xe5/0x2b0 acpi_init+0x264/0x5b0 do_one_i ---truncated---
Why
The current structured CVE record identifies a security weakness, but the root cause requires confirmation in the linked vendor material.
How
An attacker operating through the affected interface may attempt exploitation when the stated preconditions are met. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
What
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 hypervisor (ignoring the security implications of relying on what is allegedly an untrusted entity to store measurements), the TPM driver will request UC and fail: [ 1.730459] ioremap error for 0xfed40000-0xfed45000, requested 0x2, got 0x0 [ 1.732780] tpm_tis MSFT0101:00: probe with driver tpm_tis failed with error -12 Note, the '0x2' and '0x0' values refer to "enum page_cache_mode", not x86's memtypes (which frustratingly are an almost pure inversion; 2 == WB, 0 == UC). E.g. tracing mapping requests for TPM TIS yields: Mapping TPM TIS with req_type = 0 WARNING: CPU: 22 PID: 1 at arch/x86/mm/pat/memtype.c:530 memtype_reserve+0x2ab/0x460 Modules linked in: CPU: 22 UID: 0 PID: 1 Comm: swapper/0 Tainted: G W 6.16.0-rc7+ #2 VOLUNTARY Tainted: [W]=WARN Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/29/2025 RIP: 0010:memtype_reserve+0x2ab/0x460 __ioremap_caller+0x16d/0x3d0 ioremap_cache+0x17/0x30 x86_acpi_os_ioremap+0xe/0x20 acpi_os_map_iomem+0x1f3/0x240 acpi_os_map_memory+0xe/0x20 acpi_ex_system_memory_space_handler+0x273/0x440 acpi_ev_address_space_dispatch+0x176/0x4c0 acpi_ex_access_region+0x2ad/0x530 acpi_ex_field_datum_io+0xa2/0x4f0 acpi_ex_extract_from_field+0x296/0x3e0 acpi_ex_read_data_from_field+0xd1/0x460 acpi_ex_resolve_node_to_value+0x2ee/0x530 acpi_ex_resolve_to_value+0x1f2/0x540 acpi_ds_evaluate_name_path+0x11b/0x190 acpi_ds_exec_end_op+0x456/0x960 acpi_ps_parse_loop+0x27a/0xa50 acpi_ps_parse_aml+0x226/0x600 acpi_ps_execute_method+0x172/0x3e0 acpi_ns_evaluate+0x175/0x5f0 acpi_evaluate_object+0x213/0x490 acpi_evaluate_integer+0x6d/0x140 acpi_bus_get_status+0x93/0x150 acpi_add_single_object+0x43a/0x7c0 acpi_bus_check_add+0x149/0x3a0 acpi_bus_check_add_1+0x16/0x30 acpi_ns_walk_namespace+0x22c/0x360 acpi_walk_namespace+0x15c/0x170 acpi_bus_scan+0x1dd/0x200 acpi_scan_init+0xe5/0x2b0 acpi_init+0x264/0x5b0 do_one_i ---truncated---
Why
The current structured CVE record identifies a security weakness, but the root cause requires confirmation in the linked vendor material.
How
An attacker operating through the affected interface may attempt exploitation when the stated preconditions are met. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
02
Exploit reality and attack path
CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.
Observed exploitation No confirmed evidence
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.
Public PoC / exploit material None recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.
- Likely attack path
- the affected interface → vulnerable operation → cause the confidentiality, integrity or availability impact described by the vendor
- Attack surface
- Unspecified
- Privileges required
- Not stated in the selected CVSS metric
- User interaction
- Not stated in the selected CVSS metric
- Attack complexity
- Not stated in the selected CVSS metric
- Security boundary
- Not stated in the selected CVSS metric
- Weakness
?
CWE means Common Weakness Enumeration. - CWE not yet assigned
- CVSS vector
?
CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity. Not available from the selected scoring authority.- Post-exploitation / living off the land
- No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
03
Patch and workaround
Operational remediation based on structured source evidence.
- Status
?
Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change. - Fix availability varies by product
- Affected
- SUSE Linux Micro Extras 6.2:kernel-obs-build
- SUSE Linux Micro Extras 6.2:kernel-syms
- SLES 15 SP1 CHOST Images for Amazon EC2
- SLES 15 SP2 CHOST Images for Amazon EC2
- SLES 15 SP3 CHOST Images for Amazon EC2
- SLES 15 SP4 CHOST Images for Amazon EC2
- SLES 15 SP5 CHOST Images for Amazon EC2
- SLES 15 SP1 CHOST Images for Google
- SLES 15 SP2 CHOST Images for Google
- SLES 15 SP3 CHOST Images for Google
- SLES 15 SP4 CHOST Images for Google
- SLES 15 SP5 CHOST Images for Google
- SLES 15 SP1 CHOST Images for Microsoft Azure
- SLES 15 SP2 CHOST Images for Microsoft Azure
- SLES 15 SP3 CHOST Images for Microsoft Azure
- SLES 15 SP4 CHOST Images for Microsoft Azure
- SLES 15 SP5 CHOST Images for Microsoft Azure
- Action
- Use the product-specific evidence above. Patch only products with a verified fixed release, and keep every affected or under-investigation state without a matching fix in the remediation queue.
- Workaround
- No verified workaround is recorded. Limit untrusted access and use least privilege until authoritative guidance is available.
04
Evidence and provenance
Published 12 Nov 2025 · Last source change 11 May 2026, 21:44 UTC · CWE not yet assigned
CVE recordCVE.org · 5.2
CVSS sourceUnavailable
EPSS source FIRST · tracked since 2026-08-14
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2025-150393
Product sourceVendor CSAF · SUSE Product Security Team
Remediation sourceVendor CSAF · SUSE Product Security Team
CWE sourceUnavailable
NVD statusNVD not scheduled
Missing structured fields: CVSS base score, CWE classification. Missing data is not evidence of low risk; review the primary advisory.
Material change intelligence
View recent updates ↗What changed after publication
No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.
CVE published
Fixed release or patch reference recorded
Technical terms and abbreviations used in this report
- CVE
- Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
- CVSS
- Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
- EPSS
- Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
- CWE
- Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
- CNA
- CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
- CISA ADP
- Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
- NVD
- National Vulnerability Database: NIST's enrichment service for CVE records.
- CERT / CSIRT
- A computer security incident response team that publishes warnings or coordinates incident response.
- PoC
- Proof of concept: public material that demonstrates or helps reproduce exploitation.
- CSAF
- Common Security Advisory Framework: a machine-readable format for security advisories.
- LoTL
- Living off the land: abuse of legitimate tools or system functions during an attack.