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arm64/boot: Disable trapping of PMZR_EL0 writes to EL2

Type: advisorySources: OSV

In the Linux kernel, the following vulnerability has been resolved: arm64/boot: Disable trapping of PMZR_EL0 writes to EL2 __init_el2_fgt2() writes one mask to both HDFGRTR2_EL2 and HDFGWTR2_EL2. PMZR_EL0 is write-only, so its trap bit, nPMZR_EL0, exists only in HDFGWTR2_EL2 and is therefore never set: a PMZR_EL0 write from the host traps to EL2, where the nVHE hypervisor has no handler and BUG()s. The kernel never writes PMZR_EL0, but kernel.perf_user_access=1 has the PMU driver set PMUSERENR_EL0.UEN for a task with a user-read event, so a write from EL0 reaches the trap and takes the host down without a panic message. Accumulate the HDFGWTR2_EL2 bits separately, as __init_el2_fgt() already does for HDFGWTR_EL2, and set nPMZR_EL0 with the other FEAT_PMUv3p9 bits.

Products
Kernel
Affected versions
Not specified
Fixed versions
6.12.112, 6.18.55, 7.2.9
CVEs
CVE-2026-98546
Confirmed fixed CVEs
Not specified
Updated in this feed
3 Nov 2026, 18:06 UTC · Revision 1

Source evidence

arm64/boot: Disable trapping of PMZR_EL0 writes to EL2

core-osv · Original source

Published 18 Oct 2026, 15:18 UTC

In the Linux kernel, the following vulnerability has been resolved: arm64/boot: Disable trapping of PMZR_EL0 writes to EL2 __init_el2_fgt2() writes one mask to both HDFGRTR2_EL2 and HDFGWTR2_EL2. PMZR_EL0 is write-only, so its trap bit, nPMZR_EL0, exists only in HDFGWTR2_EL2 and is therefore never set: a PMZR_EL0 write from the host traps to EL2, where the nVHE hypervisor has no handler and BUG()s. The kernel never writes PMZR_EL0, but kernel.perf_user_access=1 has the PMU driver set PMUSERENR_EL0.UEN for a task with a user-read event, so a write from EL0 reaches the trap and takes the host down without a panic message. Accumulate the HDFGWTR2_EL2 bits separately, as __init_el2_fgt() already does for HDFGWTR_EL2, and set nPMZR_EL0 with the other FEAT_PMUv3p9 bits.

osv:CVE-2026-98546

Kernel

Fixed versions: 6.12.112, 6.18.55, 7.2.9

Complete source record
{
  "id": "6fd1fc04e00813291e261ca277385f9456ac569d9f45a9a27acbf79dd31ad7ce",
  "url": "https://osv.dev/vulnerability/CVE-2026-98546",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "arm64/boot: Disable trapping of PMZR_EL0 writes to EL2",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: arm64/boot: Disable trapping of PMZR_EL0 writes to EL2 __init_el2_fgt2() writes one mask to both HDFGRTR2_EL2 and HDFGWTR2_EL2. PMZR_EL0 is write-only, so its trap bit, nPMZR_EL0, exists only in HDFGWTR2_EL2 and is therefore never set: a PMZR_EL0 write from the host traps to EL2, where the nVHE hypervisor has no handler and BUG()s. The kernel never writes PMZR_EL0, but kernel.perf_user_access=1 has the PMU driver set PMUSERENR_EL0.UEN for a task with a user-read event, so a write from EL0 reaches the trap and takes the host down without a panic message. Accumulate the HDFGWTR2_EL2 bits separately, as __init_el2_fgt() already does for HDFGWTR_EL2, and set nPMZR_EL0 with the other FEAT_PMUv3p9 bits.",
    "evidence": "osv:CVE-2026-98546",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
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            "value": "6.12.112",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.18.55",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.2.9",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
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      "aliases": [
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          ],
          "database_specific": {
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          }
        },
        {
          "ranges": [
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              "type": "ECOSYSTEM",
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                  "introduced": "0"
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              ]
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            {
              "type": "ECOSYSTEM",
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                  "introduced": "6.13.0"
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                {
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            {
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          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98546.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:31.036591858Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/071f51188a5d8ec10535541255587976d12fc7d8",
        "https://git.kernel.org/stable/c/2bc6b218717b9d08f466f88209251d54bc09b207",
        "https://git.kernel.org/stable/c/bb8c90c86441c090e9036f019cf1b4d7894a2c40",
        "https://git.kernel.org/stable/c/ce71865bf43f88bed9d9218e9218e537150be506",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98546.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-98546",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98546.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-98546",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 498223,
  "published_at": "2026-10-18T15:18:14.808+00:00"
}