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CVE-2026-99082

KVM: x86: Use active memslots for the per-vCPU MMIO cache

Products / packages Linux

Published

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Severity and exploitation

Not in CISA KEV

KEV coverage does not rule out exploitation.

KEV checked 14/11/2026, 21:20:32 UTC
Linux · CVSS:3.1 · 8.8
Assessment vectorCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Severity

high8.8

CVSS measures technical severity, not the likelihood of an attack.

Known exploitation

Not listed in the checked CISA KEV catalog

Absence from CISA KEV does not rule out attacks.

Public exploit

Not established by this record

Missing evidence does not mean no public exploit exists.

Remediation

Fix status not established

No structured fix or guidance is available here. Check the latest publisher advisory.

What this means

In the Linux kernel, the following vulnerability has been resolved:

Source excerpt · Linux

Attack conditions

No attack-condition excerpt has been identified here. Review the full source description and references for authentication, network access, and configuration requirements.

Review supporting sources →

Affected versions

Check the exact model, release, and any platform requirements against your installation.

Linux · Linux

Linux

8 ranges
Linux version evidence

Compare with this publisher’s ranges. This does not inspect your installation.

affected

699023e239658e62da6f42f47d31b54788521ec1 → before 485a5286675b15b00ee850d90eaa178cc588445f

git versions

699023e239658e62da6f42f47d31b54788521ec1 → before 445e3369ac8cc1b18aedc8e8f977c68a0a326fa9

git versions

699023e239658e62da6f42f47d31b54788521ec1 → before 1c77d33d85786d36e56ca1b580fb55347fd65b47

git versions

699023e239658e62da6f42f47d31b54788521ec1 → before a63f79d9da9468952396af73e1e53330845cf876

git versions

699023e239658e62da6f42f47d31b54788521ec1 → before 7fd4e64f4bbc8c35ae8f0d2a1fb5b77a76d5b4fd

git versions

699023e239658e62da6f42f47d31b54788521ec1 → before 2566780c684c9c21241d409d790087c73070f312

git versions

699023e239658e62da6f42f47d31b54788521ec1 → before e792a9ace39d2812a5b342a1987186c7bc653204

git versions

699023e239658e62da6f42f47d31b54788521ec1 → before b3e6212dea2e4328a841ceb37f377583176dc735

git versions

unaffected

unknown

Other versions: unaffected

Linux · Linux

Linux

10 ranges
Linux version evidence

Compare with this publisher’s ranges. This does not inspect your installation.

affected

4.2

unaffected

0 → before 4.2

semver versions

5.10.273 → through 5.10.*

semver versions

5.15.224 → through 5.15.*

semver versions

6.1.191 → through 6.1.*

semver versions

6.6.160 → through 6.6.*

semver versions

6.12.114 → through 6.12.*

semver versions

6.18.58 → through 6.18.*

semver versions

7.2.12 → through 7.2.*

semver versions

7.3 → through *

original_commit_for_fix versions

unknown

Other versions: affected

Automatic dependency matching is unavailable for this record. Use the product evidence and publisher’s instructions to check your installation.

What to do

Compare your installed product and version with the affected versions above. A matching product name alone does not confirm exposure.

No structured fix or remediation guidance is available here. Check the full source description and vendor’s latest advisory for a patch or workaround; do not assume another version is safe.

cve.new guidance unless attributed to a publisher. This page does not inspect your installation.

Public exploit evidence

No public exploit reference is identified in the imported evidence. This is not a claim that no exploit exists.

Original source description

Read the full publisher description

In the Linux kernel, the following vulnerability has been resolved:

KVM: x86: Use active memslots for the per-vCPU MMIO cache

KVM tags the per-vCPU MMIO cache with a memslot generation so that a memslot update invalidates cached MMIO information. Both the fill and validation paths use kvm_memslots(), which unconditionally selects address space 0, even when the vCPU is running in SMM and using address space 1.

Commit 56f17dd3fbc4 ("kvm: x86: fix stale mmio cache bug") added the memslot generation to the cache key so that a memslot update could not leave a stale entry valid. When commit 699023e23965 ("KVM: x86: add SMM to the MMU role, support SMRAM address space") added the SMM address space, these helpers were not converted to use the active memslots.

Consequently, an update to the SMM memslots can leave an entry from the old SMM address space apparently valid after the vCPU returns to the normal address space. A guest can then cause an access to valid RAM at the same GFN to be returned to userspace as KVM_EXIT_MMIO.

Completing that exit through the VMM's RAM address space writes the backing page without going through KVM's write-tracking path. If the page backs a nested EPT table, KVM can continue using shadow translations derived from the old contents. The WARN_ON_ONCE() in kvm_mmu_write_protect_fault() catches this invalid cache and memslot combination.

Use the vCPU's active memslots when caching and validating the entry. Memslot generations are unique across address spaces, so the generation also distinguishes the normal and SMM views. This matches the MMIO SPTE cache, which already uses kvm_vcpu_memslots().

On an unpatched current-mainline kernel, a regression test that fills the cache in SMM and updates only the SMM memslots fails the intended RAM write and triggers the kvm_mmu_write_protect_fault() warning. With this change, the same test completes the RAM write without a warning. The x86/smm_test, set_memory_region_test, and memslot_modification_stress_test selftests also pass.

References

8 sources
git.kernel.org/stable/c/485a5286675b15b00ee850d90eaa178cc588445f
Source referenceLinux
git.kernel.org/stable/c/445e3369ac8cc1b18aedc8e8f977c68a0a326fa9
Source referenceLinux
git.kernel.org/stable/c/1c77d33d85786d36e56ca1b580fb55347fd65b47
Source referenceLinux
git.kernel.org/stable/c/a63f79d9da9468952396af73e1e53330845cf876
Source referenceLinux
git.kernel.org/stable/c/7fd4e64f4bbc8c35ae8f0d2a1fb5b77a76d5b4fd
Source referenceLinux
git.kernel.org/stable/c/2566780c684c9c21241d409d790087c73070f312
Source referenceLinux
View 2 more references
git.kernel.org/stable/c/e792a9ace39d2812a5b342a1987186c7bc653204
Source referenceLinux
git.kernel.org/stable/c/b3e6212dea2e4328a841ceb37f377583176dc735
Source referenceLinux

Inside the record

Evidence available

Package identity · not supplied
Version evidence
Remediation guidance · not supplied
Weakness classification · not supplied
Additional publishers · not supplied

Describes the evidence in this view, not whether the product is safe.

Original records

CVE-2026-99082

View the latest unmodified CVE JSON from the official source. It may be newer than this imported page.

cve.new JSON →

Environment requirements

These conditions apply together as specified by the publisher. A matching product name alone does not establish exposure.

Linux · platform conditions

Any condition may hold

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 4.2

Before: 5.10.273

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 4.2

Before: 5.15.224

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 4.2

Before: 6.1.191

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 4.2

Before: 6.6.160

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 4.2

Before: 6.12.114

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 4.2

Before: 6.18.58

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 4.2

Before: 7.2.12

Vulnerable product

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

From (inclusive): 4.2

Before: 7.3

Applicability preview
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    "nodes": [
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        "negate": false,
        "cpeMatch": [
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            "vulnerable": true,
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
            "versionStartIncluding": "4.2",
            "versionEndExcluding": "5.10.273"
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          {
            "vulnerable": true,
            "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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            "versionStartIncluding": "4.2",
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          {
            "vulnerable": true,
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            "vulnerable": true,
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Contributing organizations · 1
Linux

Assigning organization

2026-10-30

Timeline

All times UTC

  1. Advisory published

    Publication date supplied by the source.

  2. Source updated

    Latest modification date supplied by the source.

  3. Last imported by cve.new

    Latest catalog import, not the date we first saw this advisory.

What changed

Follow changes
No substantive changes have been recorded here yet. History starts when cve.new observes a change after tracking is enabled; earlier edits are not reconstructed.

Large field values are marked as truncated previews. Original source snapshots remain retained.