{"id":"CVE-2026-89438","title":"platform/x86: ISST: Validate logical CPU id and clos id","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nplatform/x86: ISST: Validate logical CPU id and clos id\n\nValidate max CLOS ID and logical CPU ID for core power feature.\nReject any clos level or logical CPU number gre…","severity":"medium","cvss":5.5,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","cvssSource":"vendor","cwe":["CWE-787"],"vendor":"Linux","product":"Linux","affected":["Linux >= 12a7d2cb811dd8a884dea088a2701fcb8d00136e < 0d601126c7afda9bb94dfecc8b2c0a16f20d76cb","Linux >= 12a7d2cb811dd8a884dea088a2701fcb8d00136e < c9ee2770eb95ba316a56d776b2b66666b70c194b","Linux >= 12a7d2cb811dd8a884dea088a2701fcb8d00136e < 5b032e1dda486ca41d10536bd195bd8a559af1e2","Linux >= 12a7d2cb811dd8a884dea088a2701fcb8d00136e < 82d4afadb02fb4d7d7bb9230900904c10e49ec87","Linux >= 12a7d2cb811dd8a884dea088a2701fcb8d00136e < 124e2dbabe460c2a6e7440f4ad8af560131295c9","Linux 6.4"],"published":"2026-09-11","updated":"2026-10-19","sourceUpdated":"2026-10-19T08:46:46.711Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-89438","references":[{"url":"https://git.kernel.org/stable/c/0d601126c7afda9bb94dfecc8b2c0a16f20d76cb"},{"url":"https://git.kernel.org/stable/c/c9ee2770eb95ba316a56d776b2b66666b70c194b"},{"url":"https://git.kernel.org/stable/c/5b032e1dda486ca41d10536bd195bd8a559af1e2"},{"url":"https://git.kernel.org/stable/c/82d4afadb02fb4d7d7bb9230900904c10e49ec87"},{"url":"https://git.kernel.org/stable/c/124e2dbabe460c2a6e7440f4ad8af560131295c9"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89438.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-89438"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2532236"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89438"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89438"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89438.mbox"}],"tags":["cve.org","csaf","vex","red-hat"],"epss":0.00206,"epssPercentile":0.10479,"ingestedAt":"2026-09-14T15:23:07.454Z","slug":"CVE-2026-89438","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nplatform/x86: ISST: Validate logical CPU id and clos id\n\nValidate max CLOS ID and logical CPU ID for core power feature.\nReject any clos level or logical CPU number greater than the\nsupported maximum. These are used to calculate MMIO offset.\n\n## Affected\n\n- `Linux >= 12a7d2cb811dd8a884dea088a2701fcb8d00136e < 0d601126c7afda9bb94dfecc8b2c0a16f20d76cb`\n- `Linux >= 12a7d2cb811dd8a884dea088a2701fcb8d00136e < c9ee2770eb95ba316a56d776b2b66666b70c194b`\n- `Linux >= 12a7d2cb811dd8a884dea088a2701fcb8d00136e < 5b032e1dda486ca41d10536bd195bd8a559af1e2`\n- `Linux >= 12a7d2cb811dd8a884dea088a2701fcb8d00136e < 82d4afadb02fb4d7d7bb9230900904c10e49ec87`\n- `Linux >= 12a7d2cb811dd8a884dea088a2701fcb8d00136e < 124e2dbabe460c2a6e7440f4ad8af560131295c9`\n- `Linux 6.4`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · updated 2026-10-17 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89438.json)","depth":"sunlit","depthScore":30,"depthScoreParts":{"impact":30.3,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":204117,"id":"CVE-2026-89438","ts":1789490231734,"field":"cvss","old":null,"new":"5.5"},{"seq":204116,"id":"CVE-2026-89438","ts":1789490231734,"field":"severity","old":"none","new":"medium"},{"seq":147508,"id":"CVE-2026-89438","ts":1789270211183,"field":"cvss","old":null,"new":"4.7"},{"seq":147507,"id":"CVE-2026-89438","ts":1789270211183,"field":"severity","old":"none","new":"medium"},{"seq":109266,"id":"CVE-2026-89438","ts":1789183731205,"field":"cvss","old":null,"new":"4.7"},{"seq":109265,"id":"CVE-2026-89438","ts":1789183731205,"field":"severity","old":"none","new":"medium"}]}