{"api_version":"1","generated_at":"2026-07-23T21:47:35+00:00","cve":"CVE-2026-63937","urls":{"html":"https://cve.report/CVE-2026-63937","api":"https://cve.report/api/cve/CVE-2026-63937.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-63937","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-63937"},"summary":{"title":"KVM: SEV: Use READ_ONCE() when reading entries/indices from PSC buffer","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: SEV: Use READ_ONCE() when reading entries/indices from PSC buffer\n\nUse READ_ONCE() when reading entries/indices from the guest-accessible\nPage State Change buffer to defend against TOCTOU bugs.\n\nDon't bother with READ_ONCE()/WRITE_ONCE() for cases where KVM is writing\n(and not consuming the result!), as the guest isn't supposed to touch the\nbuffer while it's being processed.  I.e. using READ_ONCE() is all about\nprotecting against misbehaving guests.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-07-19 16:17:12","updated_at":"2026-07-20 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the Linux kernel, the following vulnerability has been resolved:\n\nKVM: SEV: Use READ_ONCE() when reading entries/indices from PSC buffer\n\nUse READ_ONCE() when reading entries/indices from the guest-accessible\nPage State Change buffer to defend against TOCTOU bugs.\n\nDon't bother with READ_ONCE()/WRITE_ONCE() for cases where KVM is writing\n(and not consuming the result!), as the guest isn't supposed to touch the\nbuffer while it's being processed.  I.e. using READ_ONCE() is all about\nprotecting against misbehaving guests."}],"metrics":[{"cvssV3_1":{"baseScore":8.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","version":"3.1"}}],"providerMetadata":{"dateUpdated":"2026-07-20T13:41:39.071Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/bd232801ef1d1fd985d2d4ca3cd1d888303ca86f"},{"url":"https://git.kernel.org/stable/c/b1dfaa6f7a957726a6800135be3659fbe4bbf2a4"},{"url":"https://git.kernel.org/stable/c/edbbe88f83b524434974e84808d3093199d67c24"},{"url":"https://git.kernel.org/stable/c/c8cc238093ca6c99267032f6cfe78f59389f3157"}],"title":"KVM: SEV: Use READ_ONCE() when reading entries/indices from PSC buffer","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-63937","datePublished":"2026-07-19T14:55:34.554Z","dateReserved":"2026-07-19T07:54:57.022Z","dateUpdated":"2026-07-20T13:41:39.071Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-07-19 16:17:12","lastModifiedDate":"2026-07-20 15:16:57","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","baseScore":8.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"CHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":2,"impactScore":6}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"63937","Ordinal":"1","Title":"KVM: SEV: Use READ_ONCE() when reading entries/indices from PSC ","CVE":"CVE-2026-63937","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"63937","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: SEV: Use READ_ONCE() when reading entries/indices from PSC buffer\n\nUse READ_ONCE() when reading entries/indices from the guest-accessible\nPage State Change buffer to defend against TOCTOU bugs.\n\nDon't bother with READ_ONCE()/WRITE_ONCE() for cases where KVM is writing\n(and not consuming the result!), as the guest isn't supposed to touch the\nbuffer while it's being processed.  I.e. using READ_ONCE() is all about\nprotecting against misbehaving guests.","Type":"Description","Title":"KVM: SEV: Use READ_ONCE() when reading entries/indices from PSC "}]}}}