In the Linux kernel, the following vulnerability has been resolved:

x86/tdx: Fix off-by-one in port I/O handling

handle_in() and handle_out() in arch/x86/coco/tdx/tdx.c use:

u64 mask = GENMASK(BITS_PER_BYTE * size, 0);

GENMASK(h, l) includes bit h. For size=1 (INB), this produces
GENMASK(8, 0) = 0x1FF (9 bits) instead of GENMASK(7, 0) = 0xFF (8
bits). The mask is one bit too wide for all I/O sizes.

Fix the mask calculation.

No CVSS v4.0

Attack Vector Local

Attack Complexity High

Privileges Required High

Scope Unchanged

Confidentiality Impact None

Integrity Impact Low

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Key SSVC decision points have not yet been added.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
Linux Linux unaffected
Version Status Constraints
03149948832a078f759022ed5b92e722d8d23c26 affected < 222b7005e4519f633b4cd666226256abbab46a1a
03149948832a078f759022ed5b92e722d8d23c26 affected < c4a22154870813d10aa0b4c734a574c726f9d4b0
03149948832a078f759022ed5b92e722d8d23c26 affected < bb45f705c4440dd3c689328319b88dd28770bbb8
03149948832a078f759022ed5b92e722d8d23c26 affected < 0f63e656b1c679d32ac595de29d10c03efca6a25
Linux Linux affected
Version Status Constraints
5.19 affected —
0 unaffected < 5.19
6.12.109 unaffected ≤ 6.12.*
6.18.50 unaffected ≤ 6.18.*
7.2.4 unaffected ≤ 7.2.*
7.3-rc1 unaffected ≤ *

No data.

No data.

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Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://git.kernel.org/stable/c/0f63e656b1c679d32ac595de29d10c03efca6a25 cve-icon cve-icon cve-icon
https://git.kernel.org/stable/c/222b7005e4519f633b4cd666226256abbab46a1a cve-icon cve-icon cve-icon
https://git.kernel.org/stable/c/bb45f705c4440dd3c689328319b88dd28770bbb8 cve-icon cve-icon cve-icon
https://git.kernel.org/stable/c/c4a22154870813d10aa0b4c734a574c726f9d4b0 cve-icon cve-icon cve-icon
https://nvd.nist.gov/vuln/detail/CVE-2026-89751 cve-icon
https://www.cve.org/CVERecord?id=CVE-2026-89751 cve-icon
History

Sat, 12 Sep 2026 00:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-193
References
Metrics threat_severity

None

 cvssV3_1

{'score': 4.7, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:L/A:H'}

threat_severity

Moderate

Fri, 11 Sep 2026 23:45:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: x86/tdx: Fix off-by-one in port I/O handling handle_in() and handle_out() in arch/x86/coco/tdx/tdx.c use: u64 mask = GENMASK(BITS_PER_BYTE * size, 0); GENMASK(h, l) includes bit h. For size=1 (INB), this produces GENMASK(8, 0) = 0x1FF (9 bits) instead of GENMASK(7, 0) = 0xFF (8 bits). The mask is one bit too wide for all I/O sizes. Fix the mask calculation.
Title x86/tdx: Fix off-by-one in port I/O handling
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-09-11T19:46:55.314Z

Reserved: 2026-09-11T19:38:34.762Z

Link: CVE-2026-89751

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-09-11T20:20:06.013

Modified: 2026-09-11T20:20:06.013

Link: CVE-2026-89751

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-09-11T19:46:55Z

Links: CVE-2026-89751 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-09-12T06:00:11Z

Weaknesses