{"id":"CVE-2026-63937","title":"KVM: SEV: Use READ_ONCE() when reading entries/indices from PSC buffer","summary":"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 …","severity":"high","cvss":8.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= 9b54e248d2644be71cb394eb85f31ad99e023a05 < bd232801ef1d1fd985d2d4ca3cd1d888303ca86f","Linux >= 9b54e248d2644be71cb394eb85f31ad99e023a05 < b1dfaa6f7a957726a6800135be3659fbe4bbf2a4","Linux >= 9b54e248d2644be71cb394eb85f31ad99e023a05 < edbbe88f83b524434974e84808d3093199d67c24","Linux >= 9b54e248d2644be71cb394eb85f31ad99e023a05 < c8cc238093ca6c99267032f6cfe78f59389f3157","Linux 6.11"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-10-16T15:33:43.123685Z"},"published":"2026-07-19","updated":"2026-10-16","sourceUpdated":"2026-10-16T15:42:12.937Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-63937","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"}],"tags":["cve.org"],"epss":0.00175,"epssPercentile":0.06548,"ingestedAt":"2026-10-16T17:24:46.779Z","slug":"CVE-2026-63937","body":"## Overview\n\nIn 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.\n\n## Affected\n\n- `Linux >= 9b54e248d2644be71cb394eb85f31ad99e023a05 < bd232801ef1d1fd985d2d4ca3cd1d888303ca86f`\n- `Linux >= 9b54e248d2644be71cb394eb85f31ad99e023a05 < b1dfaa6f7a957726a6800135be3659fbe4bbf2a4`\n- `Linux >= 9b54e248d2644be71cb394eb85f31ad99e023a05 < edbbe88f83b524434974e84808d3093199d67c24`\n- `Linux >= 9b54e248d2644be71cb394eb85f31ad99e023a05 < c8cc238093ca6c99267032f6cfe78f59389f3157`\n- `Linux 6.11`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":48,"depthScoreParts":{"impact":48.4,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}