CVE-2026-64555 (GCVE-0-2026-64555)

Vulnerability from cvelistv5 – Published: 2026-07-27 20:10 – Updated: 2026-08-05 12:43
VLAI
Title
KVM: arm64: nv: Fix SPSR_EL2 restore in kvm_hyp_handle_mops()
Summary
In the Linux kernel, the following vulnerability has been resolved: KVM: arm64: nv: Fix SPSR_EL2 restore in kvm_hyp_handle_mops() kvm_hyp_handle_mops() resets the single-step state machine as part of rewinding state for a MOPS exception by modifying vcpu_cpsr() and writing the result directly into hardware. In the case of nested virtualization, vcpu_cpsr() is a synthetic value such that the rest of KVM can deal with vEL2 cleanly. That means the value requires translation before being written into hardware, which is unfortunately missing from the MOPS handler. Fix it by directly modifying SPSR_EL2 and avoiding the synthetic state altogether, which will be resynchronized on the next 'full' exit back to KVM.
Severity
8.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 2de451a329cf662beeba71f63c7f83ee24ca6642 , < 10a568010e827108d149779908850afaec898846 (git)
Affected: 2de451a329cf662beeba71f63c7f83ee24ca6642 , < 884b44256041ec6b2dcbe8e6a67384d26145cba1 (git)
Affected: 2de451a329cf662beeba71f63c7f83ee24ca6642 , < dd3b237eb7780d65eae296d3d3a70012b6e7a02f (git)
Affected: 2de451a329cf662beeba71f63c7f83ee24ca6642 , < ff1022c3de46753eb7eba2f6efd990569e66ff95 (git)
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Linux Linux Affected: 6.7
Unaffected: 0 , < 6.7 (semver)
Unaffected: 6.12.97 , ≤ 6.12.* (semver)
Unaffected: 6.18.40 , ≤ 6.18.* (semver)
Unaffected: 7.1.5 , ≤ 7.1.* (semver)
Unaffected: 7.2-rc4 , ≤ * (original_commit_for_fix)
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{
  "containers": {
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      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "arch/arm64/kvm/hyp/include/hyp/switch.h"
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              "version": "0",
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              "operator": "OR"
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: arm64: nv: Fix SPSR_EL2 restore in kvm_hyp_handle_mops()\n\nkvm_hyp_handle_mops() resets the single-step state machine as part of\nrewinding state for a MOPS exception by modifying vcpu_cpsr() and\nwriting the result directly into hardware.\n\nIn the case of nested virtualization, vcpu_cpsr() is a synthetic value\nsuch that the rest of KVM can deal with vEL2 cleanly. That means the\nvalue requires translation before being written into hardware, which is\nunfortunately missing from the MOPS handler.\n\nFix it by directly modifying SPSR_EL2 and avoiding the synthetic state\naltogether, which will be resynchronized on the next \u0027full\u0027 exit back\nto KVM."
        }
      ],
      "metrics": [
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            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
            "version": "3.1"
          },
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              "lang": "en",
              "value": "AV:L - The attacker must be executing code inside a KVM/arm64 guest on the affected host \u2014 reached via /dev/kvm and guest instruction execution, not over any network protocol. This is local access to the host machine.\nAC:L - A guest hypervisor at vEL2 triggers the MOPS exception at will by executing a main/epilogue MOPS instruction with ill-formed alignment/size parameters; there is no race and no dependence on CPU migration or single-step state, so corruption of hardware SPSR_EL2 is fully deterministic.\nPR:L - Exploitation only needs the ability to create and run a nested-capable VM (/dev/kvm access, typically granted to unprivileged tenants/kvm-group users) and to run code inside that guest\u0027s own EL2 \u2014 no privilege on the host itself.\nUI:N - The guest triggers the faulty exception path entirely on its own during normal vCPU execution; no host user or administrator action is involved.\nS:C - The bogus ERET lands the guest\u0027s PC at real EL2 under the host\u0027s own EL2 translation regime and stack, with stage-2 no longer applied \u2014 the impact crosses the guest/host virtualization boundary into a different security authority.\nC:H - Execution at EL2 with the host\u0027s TTBR0_EL2/TTBR1_EL2 active and guest-controlled registers gives read access to the entire host kernel address space and to other guests\u0027 memory.\nI:H - The guest obtains a controlled control-flow transfer into host kernel text at EL2 with all GPRs under its control, which is an arbitrary code execution / arbitrary write primitive against the host hypervisor.\nA:H - Even without successful exploitation, ERETing to an unmapped or non-executable address at EL2 takes an unexpected EL2 exception that ends in a hyp panic, bringing down the host and every VM on it."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:43:00.692Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/10a568010e827108d149779908850afaec898846"
        },
        {
          "url": "https://git.kernel.org/stable/c/884b44256041ec6b2dcbe8e6a67384d26145cba1"
        },
        {
          "url": "https://git.kernel.org/stable/c/dd3b237eb7780d65eae296d3d3a70012b6e7a02f"
        },
        {
          "url": "https://git.kernel.org/stable/c/ff1022c3de46753eb7eba2f6efd990569e66ff95"
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      ],
      "title": "KVM: arm64: nv: Fix SPSR_EL2 restore in kvm_hyp_handle_mops()",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64555",
    "datePublished": "2026-07-27T20:10:42.259Z",
    "dateReserved": "2026-07-19T15:36:31.796Z",
    "dateUpdated": "2026-08-05T12:43:00.692Z",
    "state": "PUBLISHED"
  },
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      "date": "2026-08-06",
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      "percentile": "0.02879"
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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-07-30T08:28:02+00:00",
      "cve": "CVE-2026-64555",
      "id": "CVE-2026-64555",
      "initial_release_date": "2026-07-27T00:00:00+00:00",
      "product_status:known_affected": "184",
      "product_status:known_not_affected": "90",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: KVM: arm64: nv: Fix SPSR_EL2 restore in kvm_hyp_handle_mops()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-64555.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-08-03T17:12:47Z",
      "cve": "CVE-2026-64555",
      "id": "CVE-2026-64555",
      "initial_release_date": "2026-07-28T17:07:49Z",
      "product_status:known_affected": "29",
      "product_status:known_not_affected": "269",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-64555",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-64555.json",
      "version": "4"
    }
  }
}



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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.