{
  "schemaVersion": 1,
  "attribution": [
    {
      "source": "CISA Known Exploited Vulnerabilities",
      "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog",
      "licence": "US government work"
    },
    {
      "source": "GitHub Advisory Database",
      "url": "https://github.com/advisories",
      "licence": "CC BY 4.0"
    },
    {
      "source": "Have I Been Pwned",
      "url": "https://haveibeenpwned.com/",
      "licence": "CC BY 4.0"
    },
    {
      "source": "CVE Program (CVE records)",
      "url": "https://www.cve.org/Legal/TermsOfUse",
      "licence": "CVE Terms of Use",
      "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.",
      "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy."
    },
    {
      "source": "FIRST EPSS",
      "url": "https://www.first.org/epss/",
      "licence": "free to use; FIRST requests attribution"
    }
  ],
  "record": {
    "id": "CVE-2025-40300",
    "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2025-40300",
    "idYear": 2025,
    "status": "PUBLISHED",
    "publishedAt": "2025-09-11T16:49:24.809Z",
    "updatedAt": "2026-10-15T01:09:08.416Z",
    "importedAt": "2026-10-24T01:57:34.152Z",
    "snapshot": {
      "id": "cve_2026-10-24_midnight_baseline",
      "at": "2026-10-24T00:00:00.000Z",
      "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z"
    },
    "facts": {
      "title": "x86/vmscape: Add conditional IBPB mitigation",
      "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\nx86/vmscape: Add conditional IBPB mitigation\n\nVMSCAPE is a vulnerability that exploits insufficient branch predictor\nisolation between a guest and a userspace hypervisor (like QEMU). Existing\nmitigations already protect kernel/KVM from a malicious guest. Userspace\ncan additionally be protected by flushing the branch predictors after a\nVMexit.\n\nSince it is the userspace that consumes the poisoned branch predictors,\nconditionally issue an IBPB after a VMexit and before returning to\nuserspace. Workloads that frequently switch between hypervisor and\nuserspace will incur the most overhead from the new IBPB.\n\nThis new IBPB is not integrated with the existing IBPB sites. For\ninstance, a task can use the existing speculation control prctl() to\nget an IBPB at context switch time. With this implementation, the\nIBPB is doubled up: one at context switch and another before running\nuserspace.\n\nThe intent is to integrate and optimize these cases post-embargo.\n\n[ dhansen: elaborate on suboptimal IBPB solution ]",
      "affected": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "15d45071523d89b3fb7372e2135fbd72f6af9506",
              "status": "affected",
              "versionType": "git",
              "lessThan": "ac60717f9a8d21c58617d0b34274babf24135835"
            },
            {
              "version": "15d45071523d89b3fb7372e2135fbd72f6af9506",
              "status": "affected",
              "versionType": "git",
              "lessThan": "c08192b5d6730a914dee6175bc71092ee6a65f14"
            },
            {
              "version": "15d45071523d89b3fb7372e2135fbd72f6af9506",
              "status": "affected",
              "versionType": "git",
              "lessThan": "d5490dfa35427a2967e00a4c7a1b95fdbc8ede34"
            },
            {
              "version": "15d45071523d89b3fb7372e2135fbd72f6af9506",
              "status": "affected",
              "versionType": "git",
              "lessThan": "2f4f2f8f860cb4c3336a7435ebe8dcfded0c9c6e"
            },
            {
              "version": "15d45071523d89b3fb7372e2135fbd72f6af9506",
              "status": "affected",
              "versionType": "git",
              "lessThan": "15006289e5c38b2a830e1fba221977a27598176c"
            },
            {
              "version": "15d45071523d89b3fb7372e2135fbd72f6af9506",
              "status": "affected",
              "versionType": "git",
              "lessThan": "893387c18612bb452336a5881da0d015a7e8f4a2"
            },
            {
              "version": "15d45071523d89b3fb7372e2135fbd72f6af9506",
              "status": "affected",
              "versionType": "git",
              "lessThan": "f866eef8d1c65504d30923c3f14082ad294d0e6d"
            },
            {
              "version": "15d45071523d89b3fb7372e2135fbd72f6af9506",
              "status": "affected",
              "versionType": "git",
              "lessThan": "34e5667041050711a947e260fc9ebebe08bddee5"
            },
            {
              "version": "15d45071523d89b3fb7372e2135fbd72f6af9506",
              "status": "affected",
              "versionType": "git",
              "lessThan": "d7ddc93392e4a7ffcccc86edf6ef3e64c778db52"
            },
            {
              "version": "15d45071523d89b3fb7372e2135fbd72f6af9506",
              "status": "affected",
              "versionType": "git",
              "lessThan": "459274c77b37ac63b78c928b4b4e748d1f9d05c8"
            },
            {
              "version": "15d45071523d89b3fb7372e2135fbd72f6af9506",
              "status": "affected",
              "versionType": "git",
              "lessThan": "510603f504796c3535f67f55fb0b124a303b44c8"
            },
            {
              "version": "15d45071523d89b3fb7372e2135fbd72f6af9506",
              "status": "affected",
              "versionType": "git",
              "lessThan": "9c23a90648e831d611152ac08dbcd1283d405e7f"
            },
            {
              "version": "15d45071523d89b3fb7372e2135fbd72f6af9506",
              "status": "affected",
              "versionType": "git",
              "lessThan": "2f8f173413f1cbf52660d04df92d0069c4306d25"
            },
            {
              "version": "c51f1e5f57cca88d8d5894b6fad1638f643a99d0",
              "status": "affected",
              "versionType": "git"
            },
            {
              "version": "4b3870c343a82cd2df7192cc5149c87205dcc611",
              "status": "affected",
              "versionType": "git"
            },
            {
              "version": "3.16.57",
              "status": "affected",
              "versionType": "semver",
              "lessThan": "3.17"
            },
            {
              "version": "4.4.168",
              "status": "affected",
              "versionType": "semver",
              "lessThan": "4.5"
            }
          ]
        },
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "affected",
          "versions": [
            {
              "version": "4.16",
              "status": "affected"
            },
            {
              "version": "0",
              "status": "unaffected",
              "versionType": "semver",
              "lessThan": "4.16"
            },
            {
              "version": "5.10.244",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "5.10.*"
            },
            {
              "version": "5.15.193",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "5.15.*"
            },
            {
              "version": "6.1.152",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "6.1.*"
            },
            {
              "version": "6.6.106",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "6.6.*"
            },
            {
              "version": "6.12.47",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "version": "6.16.7",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "6.16.*"
            },
            {
              "version": "6.17",
              "status": "unaffected",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ]
        }
      ]
    }
  }
}