CVE-2026-98546 (GCVE-0-2026-98546)

Vulnerability from cvelistv5 – Published: 2026-10-18 15:18 – Updated: 2026-10-19 09:21
VLAI
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.
Severity
No CVSS data available.
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 7018 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 686d8f7b592f3466f44aea653c8147611b351c83 , < bb8c90c86441c090e9036f019cf1b4d7894a2c40 (git)
Affected: 858c7bfcb35e1100b58bb63c9f562d86e09418d9 , < 071f51188a5d8ec10535541255587976d12fc7d8 (git)
Affected: 858c7bfcb35e1100b58bb63c9f562d86e09418d9 , < ce71865bf43f88bed9d9218e9218e537150be506 (git)
Affected: 858c7bfcb35e1100b58bb63c9f562d86e09418d9 , < 2bc6b218717b9d08f466f88209251d54bc09b207 (git)
Affected: 882f78400322c0aec4b641a7168adad9a66bc0c2 (git)
Affected: 6.12.25 , < 6.12.112 (semver)
Affected: 6.14.4 , < 6.15 (semver)
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Linux Linux Affected: 6.15
Unaffected: 0 , < 6.15 (semver)
Unaffected: 6.12.112 , ≤ 6.12.* (semver)
Unaffected: 6.18.55 , ≤ 6.18.* (semver)
Unaffected: 7.2.9 , ≤ 7.2.* (semver)
Unaffected: 7.3 , ≤ * (original_commit_for_fix)
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{
  "containers": {
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          "product": "Linux",
          "programFiles": [
            "Documentation/arch/arm64/booting.rst",
            "arch/arm64/include/asm/el2_setup.h"
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\narm64/boot: Disable trapping of PMZR_EL0 writes to EL2\n\n__init_el2_fgt2() writes one mask to both HDFGRTR2_EL2 and HDFGWTR2_EL2.\nPMZR_EL0 is write-only, so its trap bit, nPMZR_EL0, exists only in\nHDFGWTR2_EL2 and is therefore never set: a PMZR_EL0 write from the host\ntraps to EL2, where the nVHE hypervisor has no handler and BUG()s. The\nkernel never writes PMZR_EL0, but kernel.perf_user_access=1 has the PMU\ndriver set PMUSERENR_EL0.UEN for a task with a user-read event, so a\nwrite from EL0 reaches the trap and takes the host down without a panic\nmessage.\n\nAccumulate the HDFGWTR2_EL2 bits separately, as __init_el2_fgt() already\ndoes for HDFGWTR_EL2, and set nPMZR_EL0 with the other FEAT_PMUv3p9\nbits."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:21:29.442Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        },
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          "url": "https://git.kernel.org/stable/c/2bc6b218717b9d08f466f88209251d54bc09b207"
        }
      ],
      "title": "arm64/boot: Disable trapping of PMZR_EL0 writes to EL2",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98546",
    "datePublished": "2026-10-18T15:18:14.808Z",
    "dateReserved": "2026-09-25T10:25:14.356Z",
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      "product_status:under_investigation": "1",
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      "title": "arm64/boot: Disable trapping of PMZR_EL0 writes to EL2",
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            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\narm64/boot: Disable trapping of PMZR_EL0 writes to EL2\n\n__init_el2_fgt2() writes one mask to both HDFGRTR2_EL2 and HDFGWTR2_EL2.\nPMZR_EL0 is write-only, so its trap bit, nPMZR_EL0, exists only in\nHDFGWTR2_EL2 and is therefore never set: a PMZR_EL0 write from the host\ntraps to EL2, where the nVHE hypervisor has no handler and BUG()s. The\nkernel never writes PMZR_EL0, but kernel.perf_user_access=1 has the PMU\ndriver set PMUSERENR_EL0.UEN for a task with a user-read event, so a\nwrite from EL0 reaches the trap and takes the host down without a panic\nmessage.\n\nAccumulate the HDFGWTR2_EL2 bits separately, as __init_el2_fgt() already\ndoes for HDFGWTR_EL2, and set nPMZR_EL0 with the other FEAT_PMUv3p9\nbits."
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        ],
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        "metrics": {},
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      "cve": "CVE-2026-98546",
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      "title": "kernel: arm64/boot: Disable trapping of PMZR_EL0 writes to EL2",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-98546.json",
      "version": "3"
    }
  }
}



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