Vulnerability-Lookup

GHSA-2QHR-3XRG-MW89

Vulnerability from github – Published: 2026-10-18 18:31 – Updated: 2026-10-18 18:31

Details

In the Linux kernel, the following vulnerability has been resolved:

KVM: riscv: Fix NACL hfence entry update order

The SBI v3.0 specification (section 15.1.2) requires a nested HFENCE entry to be populated as follows: 1) find an unused entry with Config.Pending == 0 2) update the Page_Number and Page_Count words 3) update the Config word with Config.Pending set

__kvm_riscv_nacl_hfence() writes the Config word first, so the SBI implementation (or NACL hardware) can observe a pending entry with pnum/pcount values left over from the previous use of that entry, resulting in incorrect TLB flush ranges.

Write pnum and pcount first and the Config word last. Since the consumer is an external agent on coherent shared memory, use WRITE_ONCE() to stop the compiler from reordering the stores and smp_wmb() to make the parameter words globally visible before the Pending bit is set.

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{
  "affected": [],
  "aliases": [
    "CVE-2026-98639"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-10-18T16:17:17Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: riscv: Fix NACL hfence entry update order\n\nThe SBI v3.0 specification (section 15.1.2) requires a nested HFENCE\nentry to be populated as follows:\n1) find an unused entry with Config.Pending == 0\n2) update the Page_Number and Page_Count words\n3) update the Config word with Config.Pending set\n\n__kvm_riscv_nacl_hfence() writes the Config word first, so the SBI\nimplementation (or NACL hardware) can observe a pending entry with\npnum/pcount values left over from the previous use of that entry,\nresulting in incorrect TLB flush ranges.\n\nWrite pnum and pcount first and the Config word last. Since the\nconsumer is an external agent on coherent shared memory, use\nWRITE_ONCE() to stop the compiler from reordering the stores and\nsmp_wmb() to make the parameter words globally visible before the\nPending bit is set.",
  "id": "GHSA-2qhr-3xrg-mw89",
  "modified": "2026-10-18T18:31:57Z",
  "published": "2026-10-18T18:31:57Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98639"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6da466502621381fa88a6684290923d25c559266"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b3d346838ec65fac7fd83f5dbcedd13cadfffddb"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d6de766d8d26d71b714f548192099112def50a9c"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

CVE-2026-98639 (GCVE-0-2026-98639)

Vulnerability from cvelistv5 – Published: 2026-10-18 15:20 – Updated: 2026-10-19 09:23

Title

KVM: riscv: Fix NACL hfence entry update order

Summary

In the Linux kernel, the following vulnerability has been resolved: KVM: riscv: Fix NACL hfence entry update order The SBI v3.0 specification (section 15.1.2) requires a nested HFENCE entry to be populated as follows: 1) find an unused entry with Config.Pending == 0 2) update the Page_Number and Page_Count words 3) update the Config word with Config.Pending set __kvm_riscv_nacl_hfence() writes the Config word first, so the SBI implementation (or NACL hardware) can observe a pending entry with pnum/pcount values left over from the previous use of that entry, resulting in incorrect TLB flush ranges. Write pnum and pcount first and the Config word last. Since the consumer is an external agent on coherent shared memory, use WRITE_ONCE() to stop the compiler from reordering the stores and smp_wmb() to make the parameter words globally visible before the Pending bit is set.

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

3 references

URL	Tags
https://git.kernel.org/stable/c/d6de766d8d26d71b7…
https://git.kernel.org/stable/c/6da466502621381fa…
https://git.kernel.org/stable/c/b3d346838ec65fac7…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: d466c19cead5904d4d5d92adb2b213b411d3b849 , < d6de766d8d26d71b714f548192099112def50a9c (git) Affected: d466c19cead5904d4d5d92adb2b213b411d3b849 , < 6da466502621381fa88a6684290923d25c559266 (git) Affected: d466c19cead5904d4d5d92adb2b213b411d3b849 , < b3d346838ec65fac7fd83f5dbcedd13cadfffddb (git)
Linux	Linux	Affected: 6.13 Unaffected: 0 , < 6.13 (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": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "arch/riscv/kvm/nacl.c"
          ],
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          "vendor": "Linux",
          "versions": [
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              "status": "affected",
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              "versionType": "git"
            },
            {
              "lessThan": "6da466502621381fa88a6684290923d25c559266",
              "status": "affected",
              "version": "d466c19cead5904d4d5d92adb2b213b411d3b849",
              "versionType": "git"
            },
            {
              "lessThan": "b3d346838ec65fac7fd83f5dbcedd13cadfffddb",
              "status": "affected",
              "version": "d466c19cead5904d4d5d92adb2b213b411d3b849",
              "versionType": "git"
            }
          ]
        },
        {
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          "programFiles": [
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          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.13"
            },
            {
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.55",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.9",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
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            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "versionStartIncluding": "6.13",
                  "vulnerable": true
                },
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                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
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        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: riscv: Fix NACL hfence entry update order\n\nThe SBI v3.0 specification (section 15.1.2) requires a nested HFENCE\nentry to be populated as follows:\n1) find an unused entry with Config.Pending == 0\n2) update the Page_Number and Page_Count words\n3) update the Config word with Config.Pending set\n\n__kvm_riscv_nacl_hfence() writes the Config word first, so the SBI\nimplementation (or NACL hardware) can observe a pending entry with\npnum/pcount values left over from the previous use of that entry,\nresulting in incorrect TLB flush ranges.\n\nWrite pnum and pcount first and the Config word last. Since the\nconsumer is an external agent on coherent shared memory, use\nWRITE_ONCE() to stop the compiler from reordering the stores and\nsmp_wmb() to make the parameter words globally visible before the\nPending bit is set."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:23:09.004Z",
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        {
          "url": "https://git.kernel.org/stable/c/b3d346838ec65fac7fd83f5dbcedd13cadfffddb"
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      "title": "KVM: riscv: Fix NACL hfence entry update order",
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    "datePublished": "2026-10-18T15:20:10.591Z",
    "dateReserved": "2026-09-25T10:25:14.361Z",
    "dateUpdated": "2026-10-19T09:23:09.004Z",
    "state": "PUBLISHED"
  },
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}

Sightings

Author	Source	Type	Date	Other

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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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