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

Answer in brief

CVE-2026-89751 records a Unknown severity vulnerability in x86/tdx: Fix off-by-one in port I/O handling. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 11, 2026Updated Sep 11, 2026Source checked Sep 11, 2026First seen by HOL Sep 11, 2026Material review Sep 11, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Linux/Linuxgeneric	>=03149948832a078f759022ed5b92e722d8d23c26 <222b7005e4519f633b4cd666226256abbab46a1a \|\| >=03149948832a078f759022ed5b92e722d8d23c26 <c4a22154870813d10aa0b4c734a574c726f9d4b0 \|\| >=03149948832a078f759022ed5b92e722d8d23c26 <bb45f705c4440dd3c689328319b88dd28770bbb8 \|\| >=03149948832a078f759022ed5b92e722d8d23c26 <0f63e656b1c679d32ac595de29d10c03efca6a25	222b7005e4519f633b4cd666226256abbab46a1a, c4a22154870813d10aa0b4c734a574c726f9d4b0, bb45f705c4440dd3c689328319b88dd28770bbb8, 0f63e656b1c679d32ac595de29d10c03efca6a25
Linux/Linuxgeneric	5.19	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
Review the reported fix. Update Linux/Linux to 222b7005e4519f633b4cd666226256abbab46a1a if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 11, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 11, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 11, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.