{"id":"CVE-2026-89751","title":"kernel: x86/tdx: Fix off-by-one in port I/O handling (CVE-2026-89751)","summary":"A flaw was found in the Linux kernel's x86/tdx component. An off-by-one error in the `handle_in()` and `handle_out()` functions, specifically in the `GENMASK` calculation for port I/O operations, causes the mask to be one bit too wide. Thi…","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-193","vendor":"Red Hat","product":"Red Hat Enterprise Linux 9","affected":["enterprise_linux 10","enterprise_linux 8","enterprise_linux 9","openshift_container_platform 4"],"published":"2026-09-11","updated":"2026-09-21","sourceUpdated":"2026-09-21T17:37:47+00:00","source":"CSAF","sourceUrl":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89751.json","references":[{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89751.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-89751"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2532152"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89751"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89751"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89751.mbox"},{"url":"https://git.kernel.org/stable/c/0f63e656b1c679d32ac595de29d10c03efca6a25"},{"url":"https://git.kernel.org/stable/c/222b7005e4519f633b4cd666226256abbab46a1a"},{"url":"https://git.kernel.org/stable/c/bb45f705c4440dd3c689328319b88dd28770bbb8"},{"url":"https://git.kernel.org/stable/c/c4a22154870813d10aa0b4c734a574c726f9d4b0"},{"url":"https://git.kernel.org/stable/c/c6875423ad849ac234ab9812eb72f37ff8a490b4"},{"url":"https://git.kernel.org/stable/c/220011fe95fc78b2bc2d7d43893bc73957a5c811"}],"tags":["csaf","vex","red-hat","cve.org"],"epss":0.00172,"epssPercentile":0.06961,"ingestedAt":"2026-09-14T15:23:07.448Z","slug":"CVE-2026-89751","body":"## Overview\n\nA flaw was found in the Linux kernel's x86/tdx component. An off-by-one error in the `handle_in()` and `handle_out()` functions, specifically in the `GENMASK` calculation for port I/O operations, causes the mask to be one bit too wide. This incorrect handling of I/O sizes could potentially lead to unintended data access or modification during port I/O operations, which may result in information disclosure or data corruption.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · updated 2026-09-21 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89751.json)\n\n**kernel: x86/tdx: Fix off-by-one in port I/O handling** — rated Moderate by Red Hat. Released 2026-09-11, updated 2026-09-21.\n\nAffected:\n\n- Red Hat Enterprise Linux 10\n- Red Hat Enterprise Linux 8\n- Red Hat Enterprise Linux 9\n- Red Hat OpenShift Container Platform 4\n\nNo fix planned:\n\n- Red Hat Enterprise Linux 10\n- Red Hat Enterprise Linux 8\n- Red Hat Enterprise Linux 9\n- Red Hat OpenShift Container Platform 4\n\nNot affected:\n\n- Red Hat Enterprise Linux 6\n- Red Hat Enterprise Linux 7\n- Red Hat OpenShift Container Platform 4\n\n## Remediation\n\nFix deferred","depth":"sunlit","depthScore":30,"depthScoreParts":{"impact":30.3,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":208944,"id":"CVE-2026-89751","ts":1790062297644,"field":"cvss","old":"4.7","new":"5.5"},{"seq":204089,"id":"CVE-2026-89751","ts":1789490231389,"field":"cvss","old":null,"new":"4.7"},{"seq":204088,"id":"CVE-2026-89751","ts":1789490231389,"field":"severity","old":"none","new":"medium"},{"seq":147670,"id":"CVE-2026-89751","ts":1789270211818,"field":"cvss","old":null,"new":"4.7"},{"seq":147669,"id":"CVE-2026-89751","ts":1789270211818,"field":"severity","old":"none","new":"medium"},{"seq":109424,"id":"CVE-2026-89751","ts":1789183731859,"field":"cvss","old":null,"new":"4.7"},{"seq":109423,"id":"CVE-2026-89751","ts":1789183731859,"field":"severity","old":"none","new":"medium"}]}