{"id":"CVE-2026-63939","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-63939","generatedAt":"2026-10-28T00:28:10.482Z","title":"In the Linux kernel, the following vulnerability has been resolved: KVM: SEV: Compute the correct max length of the in-GHCB scratch area When setting the length of the GHCB scratch area, and the area is in the GHCB shared buffer, set the effective…","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: SEV: Compute the correct max length of the in-GHCB scratch area\n\nWhen setting the length of the GHCB scratch area, and the area is in the\nGHCB shared buffer, set the effective length of the scratch area to the max\npossible size given the start of the guest-provided pointer, and the end of\nthe shared buffer.\n\nThe code was \"fine\" when first introduced, as KVM doesn't consult the\nlength of the buffer when emulating MMIO, because the passed in @len always\nspecifies the *max* size required.  But for PSC requests, the incoming @len\nis just the minimum length (to process the header), and KVM needs to know\nthe full size of the scratch area to avoid buffer overflows (spoiler alert).\n\nOpportunistically rename @len => @min_len to better reflect its role.","published":"2026-07-19T16:17:12.000Z","lastModified":"2026-10-19T21:17:13.000Z","status":"Awaiting Analysis","sourceIdentifier":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","cvss":{"version":"3.1","score":9.3,"severity":"CRITICAL","vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H"},"cwe":["CWE-122"],"affected":[],"epss":{"score":0.00201,"percentile":0.09849,"date":"2026-10-26","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (0.20%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[],"references":[{"url":"https://git.kernel.org/stable/c/5867d7e202e09f037cefe77f7af4413c7c0fa088","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/6644565527c4c5f507088b1c9ddf72de47790b68","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/6ca9400d36005ffdca25f80186bea781c7e1dc4c","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/9f0a9e780f02c02d025a190f1885e1d1d73b87bd","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-63939","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}