CVE-2026-98638 (GCVE-0-2026-98638)

Vulnerability from cvelistv5 – Published: 2026-10-18 15:20 – Updated: 2026-10-19 09:23
VLAI
Title
KVM: arm64: Validate the SVE vector length in pkvm_vcpu_init_sve()
Summary
In the Linux kernel, the following vulnerability has been resolved: KVM: arm64: Validate the SVE vector length in pkvm_vcpu_init_sve() pkvm_vcpu_init_sve() clamps only the upper bound of the host-provided sve_max_vl, so an invalid vector length reaches sve_state_size_from_vl() and the WARN_ON() there, which is fatal at EL2. The existing !sve_state_size test rejects such a length, but only after the macro has run. Check sve_vl_valid() before deriving the state size. A valid length cannot yield a zero size, so the !sve_state_size test goes with it.
Severity
No CVSS data available.
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 6848 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 5db1bef933427aa467ad89c7b695a84a6b4afe16 , < faf66e55e87498ab4bf88cdf9a629e61b3f2d3bc (git)
Affected: 5db1bef933427aa467ad89c7b695a84a6b4afe16 , < bae3e4493046de4fefa15f809d9b8dc114e84a3d (git)
Affected: 5db1bef933427aa467ad89c7b695a84a6b4afe16 , < 2a2eb10795a1e495aebc7f829ccecb72c05b4fd9 (git)
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Linux Linux Affected: 6.16
Unaffected: 0 , < 6.16 (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": {
    "cna": {
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        {
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          "product": "Linux",
          "programFiles": [
            "arch/arm64/kvm/hyp/nvhe/pkvm.c"
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      ],
      "cpeApplicability": [
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                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: arm64: Validate the SVE vector length in pkvm_vcpu_init_sve()\n\npkvm_vcpu_init_sve() clamps only the upper bound of the host-provided\nsve_max_vl, so an invalid vector length reaches sve_state_size_from_vl()\nand the WARN_ON() there, which is fatal at EL2. The existing\n!sve_state_size test rejects such a length, but only after the macro has\nrun.\n\nCheck sve_vl_valid() before deriving the state size. A valid length\ncannot yield a zero size, so the !sve_state_size test goes with it."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:23:08.052Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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        {
          "url": "https://git.kernel.org/stable/c/2a2eb10795a1e495aebc7f829ccecb72c05b4fd9"
        }
      ],
      "title": "KVM: arm64: Validate the SVE vector length in pkvm_vcpu_init_sve()",
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  "cveMetadata": {
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98638",
    "datePublished": "2026-10-18T15:20:09.380Z",
    "dateReserved": "2026-09-25T10:25:14.361Z",
    "dateUpdated": "2026-10-19T09:23:08.052Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
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      "date": "2026-11-03",
      "epss": "0.00166",
      "percentile": "0.05889"
    },
    "microsoft_vex": {
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      "cve": "CVE-2026-98638",
      "id": "msrc_CVE-2026-98638",
      "initial_release_date": "2026-10-20T22:24:47.000Z",
      "product_status:under_investigation": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "KVM: arm64: Validate the SVE vector length in pkvm_vcpu_init_sve()",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-98638.json",
      "version": "2"
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    "nvd": {
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            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: arm64: Validate the SVE vector length in pkvm_vcpu_init_sve()\n\npkvm_vcpu_init_sve() clamps only the upper bound of the host-provided\nsve_max_vl, so an invalid vector length reaches sve_state_size_from_vl()\nand the WARN_ON() there, which is fatal at EL2. The existing\n!sve_state_size test rejects such a length, but only after the macro has\nrun.\n\nCheck sve_vl_valid() before deriving the state size. A valid length\ncannot yield a zero size, so the !sve_state_size test goes with it."
          }
        ],
        "id": "CVE-2026-98638",
        "lastModified": "2026-10-19T10:19:28.037",
        "metrics": {},
        "published": "2026-10-18T16:17:16.920",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/2a2eb10795a1e495aebc7f829ccecb72c05b4fd9"
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          },
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        "vulnStatus": "Received"
      }
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      "aggregate_severity": "Moderate",
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      "product_status:known_not_affected": "278",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: KVM: arm64: Validate the SVE vector length in pkvm_vcpu_init_sve()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-98638.json",
      "version": "3"
    }
  }
}



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