# CVE-2026-89751

## Summary

- **CVE ID:** CVE-2026-89751
- **Severity:** UNKNOWN
- **CVSS Score:** 1.51
- **CWE:** N/A
- **Published:** Sep 11, 2026
- **Last Modified:** Sep 16, 2026

## 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.

## Affected Products

- Linux — Linux (03149948832a078f759022ed5b92e722d8d23c26)
- Linux — Linux (5.19)
- Linux — Linux (0)
- Linux — Linux (6.12.109)
- Linux — Linux (6.18.50)
- Linux — Linux (7.2.4)
- Linux — Linux (7.3-rc1)
- Linux — Linux (6.1.188)
- Linux — Linux (6.6.157)

## References

- [CNA](https://git.kernel.org/stable/c/222b7005e4519f633b4cd666226256abbab46a1a)
- [CNA](https://git.kernel.org/stable/c/c4a22154870813d10aa0b4c734a574c726f9d4b0)
- [CNA](https://git.kernel.org/stable/c/bb45f705c4440dd3c689328319b88dd28770bbb8)
- [CNA](https://git.kernel.org/stable/c/0f63e656b1c679d32ac595de29d10c03efca6a25)
- [CNA](https://git.kernel.org/stable/c/c6875423ad849ac234ab9812eb72f37ff8a490b4)
- [CNA](https://git.kernel.org/stable/c/220011fe95fc78b2bc2d7d43893bc73957a5c811)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.17%
- **EPSS Percentile:** 7.0

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-18._