CVE-2026-64286 (GCVE-0-2026-64286)

Vulnerability from cvelistv5 – Published: 2026-07-25 08:49 – Updated: 2026-08-05 12:40
VLAI
Title
KVM: arm64: Clear __hyp_running_vcpu when flushing the pKVM hyp vCPU
Summary
In the Linux kernel, the following vulnerability has been resolved: KVM: arm64: Clear __hyp_running_vcpu when flushing the pKVM hyp vCPU flush_hyp_vcpu() copies the host vCPU context into the hyp's private vCPU on every run. ctxt_to_vcpu() expects a guest context to have a NULL __hyp_running_vcpu, which is only ever set on the host context, so that it resolves the vCPU via container_of(). While this is generally the case, flush_hyp_vcpu() copies the context verbatim and does not enforce this, so a value provided by the host is dereferenced at EL2 (host -> EL2). Fix by clearing __hyp_running_vcpu after the copy.
Severity
8.2 (High)
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: be66e67f175096f283c9d5614c4991fc9e7ed975 , < 477145860dba4c30f0b4e36f02f4c5291c1c888b (git)
Affected: be66e67f175096f283c9d5614c4991fc9e7ed975 , < dfaef40d8a1533940fc1af788d70fce07362b4ce (git)
Affected: be66e67f175096f283c9d5614c4991fc9e7ed975 , < 6bea2f8becdb20d34378493c3b77a9b9cf8c6cfa (git)
Affected: be66e67f175096f283c9d5614c4991fc9e7ed975 , < d4f4d61715d1061ba83b88196a3605662be30750 (git)
Affected: be66e67f175096f283c9d5614c4991fc9e7ed975 , < e8042f6e1d7befb2fb6b10a75918642bcd0acf9a (git)
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Linux Linux Affected: 6.2
Unaffected: 0 , < 6.2 (semver)
Unaffected: 6.6.145 , ≤ 6.6.* (semver)
Unaffected: 6.12.97 , ≤ 6.12.* (semver)
Unaffected: 6.18.39 , ≤ 6.18.* (semver)
Unaffected: 7.1.4 , ≤ 7.1.* (semver)
Unaffected: 7.2-rc1 , ≤ * (original_commit_for_fix)
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{
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      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "arch/arm64/kvm/hyp/nvhe/hyp-main.c"
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              "status": "unaffected",
              "version": "7.1.4",
              "versionType": "semver"
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              "status": "unaffected",
              "version": "7.2-rc1",
              "versionType": "original_commit_for_fix"
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      ],
      "cpeApplicability": [
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: arm64: Clear __hyp_running_vcpu when flushing the pKVM hyp vCPU\n\nflush_hyp_vcpu() copies the host vCPU context into the hyp\u0027s private\nvCPU on every run. ctxt_to_vcpu() expects a guest context to have a\nNULL __hyp_running_vcpu, which is only ever set on the host context, so\nthat it resolves the vCPU via container_of(). While this is generally\nthe case, flush_hyp_vcpu() copies the context verbatim and does not\nenforce this, so a value provided by the host is dereferenced at EL2\n(host -\u003e EL2).\n\nFix by clearing __hyp_running_vcpu after the copy."
        }
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            "baseSeverity": "HIGH",
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            "version": "3.1"
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              "value": "AV:L - A malicious or compromised local EL1 host can place the pointer in the host vCPU context and trigger the vulnerable pKVM path through KVM_RUN; no remote input path reaches it.\nAC:L - The attacker-selected pointer is copied and dereferenced deterministically on every vCPU run, without a race, and EL2 addresses of host-donated metadata are derivable by the host.\nPR:H - Exploitation requires host-kernel control or an equivalent arbitrary kernel write. The KVM userspace register API does not expose __hyp_running_vcpu, and user namespaces do not bypass this restriction.\nUI:N - Once the malicious host context is prepared, invoking the vCPU run path requires no action by another user.\nS:C - The vulnerability crosses the intended isolation boundary from the untrusted EL1 host into the pKVM hypervisor at EL2 and can affect protected-VM resources.\nC:H - The forged pointer drives EL2-private memory dereferences during system-register restoration. Chaining these reads with the write-side corruption can compromise EL2 and expose hypervisor or protected-guest memory.\nI:H - The system-register save path can write through the attacker-selected vCPU pointer into EL2-accessible memory. This can corrupt trusted hypervisor metadata and plausibly enable control-flow or protected-guest state modification.\nA:H - An invalid or unmapped pointer causes a synchronous EL2 fault followed by the nVHE HYP panic handler, which explicitly panics the host kernel."
            }
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        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/e8042f6e1d7befb2fb6b10a75918642bcd0acf9a"
        }
      ],
      "title": "KVM: arm64: Clear __hyp_running_vcpu when flushing the pKVM hyp vCPU",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64286",
    "datePublished": "2026-07-25T08:49:27.542Z",
    "dateReserved": "2026-07-19T15:36:31.778Z",
    "dateUpdated": "2026-08-05T12:40:35.861Z",
    "state": "PUBLISHED"
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      "percentile": "0.06649"
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      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "KVM: arm64: Clear __hyp_running_vcpu when flushing the pKVM hyp vCPU",
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      "version": "2"
    },
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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-05T14:10:29+00:00",
      "cve": "CVE-2026-64286",
      "id": "CVE-2026-64286",
      "initial_release_date": "2026-07-25T00:00:00+00:00",
      "product_status:known_affected": "108",
      "product_status:known_not_affected": "166",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: KVM: arm64: Clear __hyp_running_vcpu when flushing the pKVM hyp vCPU",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-64286.json",
      "version": "3"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.