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Linux CVE-2026-89751

| EUVDEUVD-2026-76663
2026-09-11 Linux GHSA-pv9x-wp8q-3x5j

Lifecycle Timeline

2
Patch available
Sep 11, 2026 - 21:18 EUVD
CVE Published
Sep 11, 2026 - 19:46 cve.org
UNKNOWN (no severity yet)

DescriptionCVE.org

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.

Analysis

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). …

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CVE-2026-89751 vulnerability details – vuln.today

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