CVE-2026-98719

Status: ReceivedUnscored—

Severity—Unscored

Exploitation probability0.17 %higher than 5% of CVEs

Active exploitationNonot in the CISA catalog

Public exploitNot knownno public code found

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

KVM: SEV: Nullify "have run CPUs" mask pointer when freeing it

Nullify have_run_cpus when freeing the mask, particularly in the error path of __sev_guest_init(), so that KVM doesn't have to subtly use sev->active to track whether or not the mask has been freed. As pointed out by Sashiko, blindly freeing the mask in sev_vm_destroy() results in a double-free if the mask is freed if __sev_guest_init() fails.

Throw the logic in a helper as nullifying the pointer is frustratingly difficult and weird due to have_run_cpus being a single-entry array when CPUMASK_OFFSTACK=n.

Read full descriptionShow less

Deliberately don't use CPUMASK_VAR_NULL, as it's not directly assignable when the cpumask is on-stack, e.g. requires using a local variable and a memcpy(), which is beyond ridiculous. Furthermore, while clearing the on-stack bitmask is an unnecessary and arguably unwanted side effect, KVM absolutely relies on '0' being the "null" value given that the struct is zero-allocated.

Opportunistically add an alloc() helper to pair with free(); there are just enough call sites to make doing so worthwhile.

CVSS

NVD hasn't assigned a CVSS score to this CVE (common since the April 2026 policy change).

Exploitation probability (EPSS)

Probability of exploitation in the next 30 days: 0.17 %
Percentile among all scored CVEs: 5
Score date: 10/20/2026

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

Affected technologies (1)

⚠ AI-inferred from the description — NVD hasn't analyzed this CVE yet, these aren't verified CPEs.

Linux — Linux Kernel^AI

References

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Raw JSON (NVD)

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{
  "id": "CVE-2026-98719",
  "cveTags": [],
  "metrics": {},
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6aef7cf800098749ff5d660222efaf6e01e98c09",
              "lessThan": "b1de3ebf59507e0edacaa5cfa2225bc1869e1b63",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "9784e5ca91b37b387f3f414af4340c54f7a63566",
              "lessThan": "0fbc7fec2242de6c3dcea6de55573c428e820173",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "12c1f6e03f944e399bd2c88441dca5dc702b95a5",
              "lessThan": "8abbc76120a74bfba1851bd97528099d715e45c6",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "arch/x86/kvm/svm/sev.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.18.55",
              "lessThan": "6.18.56",
              "versionType": "semver"
            },
            {
              "status": "affected",
              "version": "7.2.9",
              "lessThan": "7.2.10",
              "versionType": "semver"
            }
          ],
          "programFiles": [
            "arch/x86/kvm/svm/sev.c"
          ],
          "defaultStatus": "unaffected"
        }
      ]
    }
  ],
  "published": "2026-10-18T16:17:25.463",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/0fbc7fec2242de6c3dcea6de55573c428e820173",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/8abbc76120a74bfba1851bd97528099d715e45c6",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/b1de3ebf59507e0edacaa5cfa2225bc1869e1b63",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: SEV: Nullify \"have run CPUs\" mask pointer when freeing it\n\nNullify have_run_cpus when freeing the mask, particularly in the error path\nof __sev_guest_init(), so that KVM doesn't have to subtly use sev->active\nto track whether or not the mask has been freed.  As pointed out by Sashiko,\nblindly freeing the mask in sev_vm_destroy() results in a double-free if\nthe mask is freed if __sev_guest_init() fails.\n\nThrow the logic in a helper as nullifying the pointer is frustratingly\ndifficult and weird due to have_run_cpus being a single-entry array when\nCPUMASK_OFFSTACK=n.  Deliberately don't use CPUMASK_VAR_NULL, as it's not\ndirectly assignable when the cpumask is on-stack, e.g. requires using a\nlocal variable and a memcpy(), which is beyond ridiculous.  Furthermore,\nwhile clearing the on-stack bitmask is an unnecessary and arguably unwanted\nside effect, KVM absolutely relies on '0' being the \"null\" value given that\nthe struct is zero-allocated.\n\nOpportunistically add an alloc() helper to pair with free(); there are just\nenough call sites to make doing so worthwhile."
    }
  ],
  "lastModified": "2026-10-19T10:19:36.137",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}