x86/tdx: Fix off-by-one in port I/O handling
Priority LOW 22Published · Updated
Key facts
- Attack vector
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- Privileges required
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- User interaction
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- Attack complexity
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- Impact type
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- Confidentiality · integrity · availability
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- Fix status
- Partial Red Hat: 5 without a fix
No CVSS vector from any source. Fix status from CNA and Red Hat.
Summary
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.
Why it matters now
EPSS 0.00173 6th percentileScored 2026-11-07
Fix Partial Linux (Linux): 6.1.188, 6.6.157, 6.12.109 +3Red Hat: 5 without a fix
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
Remediation
- Fix · CNA Linux (Linux) Fixed in 6.1.188, 6.6.157, 6.12.109, 6.18.50, 7.2.4, 7.3
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 8 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 9 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 4 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 5 | Affected | No fix yet: Fix deferred |
Not affected: 3 products
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat OpenShift Container Platform 4
Timeline
- 2026-10-02 Threatist record created from CVE-2026-89751
- 2026-10-03 Alias added: GHSA-pv9x-wp8q-3x5j
- 2026-10-19 Fix available: Linux/[email protected] · CNA
- 2026-11-06 Affected versions changed · Red Hat
References
Other 6
- https://git.kernel.org/stable/c/c6875423ad849ac234ab9812eb72f37ff8a490b4
- https://git.kernel.org/stable/c/220011fe95fc78b2bc2d7d43893bc73957a5c811
- https://git.kernel.org/stable/c/222b7005e4519f633b4cd666226256abbab46a1a
- https://git.kernel.org/stable/c/c4a22154870813d10aa0b4c734a574c726f9d4b0
- https://git.kernel.org/stable/c/bb45f705c4440dd3c689328319b88dd28770bbb8
- https://git.kernel.org/stable/c/0f63e656b1c679d32ac595de29d10c03efca6a25
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Sources
- CVE-2026-89751 · CVE Program
- CVE-2026-89751 · NVD
- FIRST EPSS
- GHSA-pv9x-wp8q-3x5j · GitHub Advisory Database · CC BY 4.0
- CVE-2026-89751 · Red Hat security data · CC BY 4.0
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