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

Type: advisorySource: Official CVE List1 source record

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 space

Announced Source revision 1
Original source ↗

CVE-2026-99082

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-99082

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Linux

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "699023e239658e62da6f42f47d31b54788521ec1",
        "lessThan": "a63f79d9da9468952396af73e1e53330845cf876",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "699023e239658e62da6f42f47d31b54788521ec1",
        "lessThan": "7fd4e64f4bbc8c35ae8f0d2a1fb5b77a76d5b4fd",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "699023e239658e62da6f42f47d31b54788521ec1",
        "lessThan": "2566780c684c9c21241d409d790087c73070f312",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "699023e239658e62da6f42f47d31b54788521ec1",
        "lessThan": "e792a9ace39d2812a5b342a1987186c7bc653204",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "699023e239658e62da6f42f47d31b54788521ec1",
        "lessThan": "b3e6212dea2e4328a841ceb37f377583176dc735",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "arch/x86/kvm/x86.h"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "4.2"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "4.2",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "6.6.160",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.114",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.58",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "7.2.12",
        "versionType": "semver",
        "lessThanOrEqual": "7.2.*"
      },
      {
        "status": "unaffected",
        "version": "7.3",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "arch/x86/kvm/x86.h"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-99082

Source reference: /cveMetadata/cveId

Publisher severity

high

Source reference: /containers/cna/metrics

Event
#55751 · Revision 1
Added to Heist Feed
Publisher date
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