CVE-2026-72278 (GCVE-0-2026-72278)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:54 – Updated: 2026-08-17 05:42
VLAI
Title
KVM: arm64: nv: Re-translate VNCR before injecting abort
Summary
In the Linux kernel, the following vulnerability has been resolved: KVM: arm64: nv: Re-translate VNCR before injecting abort KVM faults in the VNCR page with FOLL_WRITE whenever the guest aborts for a write, similar to how a regular stage-2 mapping is handled. It is entirely possible that the guest reads from the VNCR before writing to it, in which case the PFN could only be read-only. Invalidate the VNCR TLB and re-fetch the translation upon taking a VNCR abort, allowing the host mapping to be faulted in for write the second time around. Interestingly enough, this also satisfies the ordering requirements of FEAT_ETS2/3 between descriptor updates and MMU faults.
Severity
9.3 (Critical)
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 2a359e072596fcb2e9e85017a865e3618a2fe5b5 , < ea7a76d7d614b5f82b4d0785f9af3550e860a71a (git)
Affected: 2a359e072596fcb2e9e85017a865e3618a2fe5b5 , < 0a5dd8cf4d58ea28da132c2097cd1c525302ac48 (git)
Affected: 2a359e072596fcb2e9e85017a865e3618a2fe5b5 , < bb645aa0a4caeaf7f9cd32e9a948594d434c1a8f (git)
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Linux Linux Affected: 6.16
Unaffected: 0 , < 6.16 (semver)
Unaffected: 6.18.40 , ≤ 6.18.* (semver)
Unaffected: 7.1.5 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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{
  "containers": {
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      "affected": [
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          "product": "Linux",
          "programFiles": [
            "arch/arm64/kvm/nested.c"
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: arm64: nv: Re-translate VNCR before injecting abort\n\nKVM faults in the VNCR page with FOLL_WRITE whenever the guest aborts\nfor a write, similar to how a regular stage-2 mapping is handled. It is\nentirely possible that the guest reads from the VNCR before writing to\nit, in which case the PFN could only be read-only.\n\nInvalidate the VNCR TLB and re-fetch the translation upon taking a VNCR\nabort, allowing the host mapping to be faulted in for write the second\ntime around. Interestingly enough, this also satisfies the ordering\nrequirements of FEAT_ETS2/3 between descriptor updates and MMU faults."
        }
      ],
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            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The flaw is reached only when an arm64 nested-KVM L1 hypervisor triggers VNCR_EL2 data aborts (ESR_ELx_EC_DABT_CUR with ESR_ELx_VNCR) handled via KVM_RUN through kvm_handle_vncr_abort(); no network, adjacent-radio, or physical-device path reaches this code.\nAC:L - An attacker controlling an L1 nested-hypervisor VM can reliably issue read-then-write VNCR accesses, remap the VNCR page, and force translation/permission faults; nested virt on arm64 cloud hosts is an attacker-selectable deployment, not an uncontrollable condition.\nPR:N - Exploitation requires no host root or init-namespace capabilities beyond running hypervisor code in a tenant KVM guest on an arm64 host with nested virtualization enabled; the attacker operates entirely from within their assigned VM, consistent with other arm64 KVM nested-virt CVE scoring.\nUI:N - No victim user or administrator action is required beyond the attacker operating their own nested-virtualization workload; VNCR faults, pseudo-TLB reuse, and repeated write triggers are fully attacker-driven from within the guest.\nS:C - Stale VNCR pseudo-TLB and fixmap state lets guest-controlled faults cause host KVM to map and access the wrong guest physical pages when emulating EL2 register state, crossing the guest-to-hypervisor security boundary beyond the guest\u0027s intended authority.\nC:H - Reusing a cached VNCR translation without re-walking guest page tables can make the host read unintended guest physical pages through the per-CPU fixmap during VNCR emulation, providing a stale-translation information-disclosure primitive across guest memory views.\nI:H - Without re-translation on write aborts, a writable host fixmap established under a stale read-only fault can let the hypervisor write nested EL2 register values into the wrong guest physical page, corrupting memory the VMM expected to isolate.\nA:H - Incorrect permission/external-abort injection on VNCR write faults after a prior read leaves nested hypervisors unable to progress and can drive tight host-side fault-handling loops, causing CPU exhaustion and denial of service to co-resident workloads."
            }
          ]
        }
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        "dateUpdated": "2026-08-17T05:42:13.824Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/0a5dd8cf4d58ea28da132c2097cd1c525302ac48"
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          "url": "https://git.kernel.org/stable/c/bb645aa0a4caeaf7f9cd32e9a948594d434c1a8f"
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    "datePublished": "2026-08-15T05:54:59.698Z",
    "dateReserved": "2026-08-09T03:40:39.916Z",
    "dateUpdated": "2026-08-17T05:42:13.824Z",
    "state": "PUBLISHED"
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          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: arm64: nv: Re-translate VNCR before injecting abort\n\nKVM faults in the VNCR page with FOLL_WRITE whenever the guest aborts\nfor a write, similar to how a regular stage-2 mapping is handled. It is\nentirely possible that the guest reads from the VNCR before writing to\nit, in which case the PFN could only be read-only.\n\nInvalidate the VNCR TLB and re-fetch the translation upon taking a VNCR\nabort, allowing the host mapping to be faulted in for write the second\ntime around. Interestingly enough, this also satisfies the ordering\nrequirements of FEAT_ETS2/3 between descriptor updates and MMU faults."
          }
        ],
        "id": "CVE-2026-72278",
        "lastModified": "2026-08-17T06:18:30.363",
        "metrics": {
          "cvssMetricV31": [
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                "baseSeverity": "CRITICAL",
                "confidentialityImpact": "HIGH",
                "integrityImpact": "HIGH",
                "privilegesRequired": "NONE",
                "scope": "CHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H",
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        "vulnStatus": "Received"
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      "current_release_date": "2026-08-19T05:25:34+00:00",
      "cve": "CVE-2026-72278",
      "id": "CVE-2026-72278",
      "initial_release_date": "2026-08-15T00:00:00+00:00",
      "product_status:known_affected": "76",
      "product_status:known_not_affected": "198",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: KVM: arm64: nv: Re-translate VNCR before injecting abort",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-72278.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-08-21T00:42:07Z",
      "cve": "CVE-2026-72278",
      "id": "CVE-2026-72278",
      "initial_release_date": "2026-08-21T00:42:07Z",
      "product_status:known_not_affected": "284",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-72278",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-72278.json",
      "version": "2"
    }
  }
}



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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.

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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.



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