{"id":"CVE-2026-89751","title":"x86/tdx: Fix off-by-one in port I/O handling","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nx86/tdx: Fix off-by-one in port I/O handling\n\nhandle_in() and handle_out() in arch/x86/coco/tdx/tdx.c use:\n\n    u64 mask = GENMASK(BITS_PER_BYTE * size, 0);\n\nGENMASK(h,…","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":"Linux","product":"Linux","affected":["Linux >= 03149948832a078f759022ed5b92e722d8d23c26 < c6875423ad849ac234ab9812eb72f37ff8a490b4","Linux >= 03149948832a078f759022ed5b92e722d8d23c26 < 220011fe95fc78b2bc2d7d43893bc73957a5c811","Linux >= 03149948832a078f759022ed5b92e722d8d23c26 < 222b7005e4519f633b4cd666226256abbab46a1a","Linux >= 03149948832a078f759022ed5b92e722d8d23c26 < c4a22154870813d10aa0b4c734a574c726f9d4b0","Linux >= 03149948832a078f759022ed5b92e722d8d23c26 < bb45f705c4440dd3c689328319b88dd28770bbb8","Linux >= 03149948832a078f759022ed5b92e722d8d23c26 < 0f63e656b1c679d32ac595de29d10c03efca6a25","Linux 5.19"],"published":"2026-09-11","updated":"2026-10-19","sourceUpdated":"2026-10-19T08:52:05.025Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-89751","references":[{"url":"https://git.kernel.org/stable/c/c6875423ad849ac234ab9812eb72f37ff8a490b4"},{"url":"https://git.kernel.org/stable/c/220011fe95fc78b2bc2d7d43893bc73957a5c811"},{"url":"https://git.kernel.org/stable/c/222b7005e4519f633b4cd666226256abbab46a1a"},{"url":"https://git.kernel.org/stable/c/c4a22154870813d10aa0b4c734a574c726f9d4b0"},{"url":"https://git.kernel.org/stable/c/bb45f705c4440dd3c689328319b88dd28770bbb8"},{"url":"https://git.kernel.org/stable/c/0f63e656b1c679d32ac595de29d10c03efca6a25"},{"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"}],"tags":["cve.org","csaf","vex","red-hat"],"epss":0.00173,"epssPercentile":0.06648,"ingestedAt":"2026-09-14T15:23:07.448Z","slug":"CVE-2026-89751","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nx86/tdx: Fix off-by-one in port I/O handling\n\nhandle_in() and handle_out() in arch/x86/coco/tdx/tdx.c use:\n\n    u64 mask = GENMASK(BITS_PER_BYTE * size, 0);\n\nGENMASK(h, l) includes bit h. For size=1 (INB), this produces\nGENMASK(8, 0) = 0x1FF (9 bits) instead of GENMASK(7, 0) = 0xFF (8\nbits). The mask is one bit too wide for all I/O sizes.\n\nFix the mask calculation.\n\n## Affected\n\n- `Linux >= 03149948832a078f759022ed5b92e722d8d23c26 < c6875423ad849ac234ab9812eb72f37ff8a490b4`\n- `Linux >= 03149948832a078f759022ed5b92e722d8d23c26 < 220011fe95fc78b2bc2d7d43893bc73957a5c811`\n- `Linux >= 03149948832a078f759022ed5b92e722d8d23c26 < 222b7005e4519f633b4cd666226256abbab46a1a`\n- `Linux >= 03149948832a078f759022ed5b92e722d8d23c26 < c4a22154870813d10aa0b4c734a574c726f9d4b0`\n- `Linux >= 03149948832a078f759022ed5b92e722d8d23c26 < bb45f705c4440dd3c689328319b88dd28770bbb8`\n- `Linux >= 03149948832a078f759022ed5b92e722d8d23c26 < 0f63e656b1c679d32ac595de29d10c03efca6a25`\n- `Linux 5.19`\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 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)","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"}]}