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CVE-2026-89751· NVD / CVE Program· CNA Linux

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

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 exploit Fix available
Published
Sep 11, 2026
Updated
Sep 14, 2026
EPSS
0.2% · 11th percentile
CWE
—
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Action score

0

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Low priority for now.

CVSS
0 / 40 · —
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

Affected systems

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Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 5.19affected
    • 03149948832a078f759022ed5b92e722d8d23c26 and later · before c6875423ad849ac234ab9812eb72f37ff8a490b4affected · git
    • 03149948832a078f759022ed5b92e722d8d23c26 and later · before 220011fe95fc78b2bc2d7d43893bc73957a5c811affected · git
    • 03149948832a078f759022ed5b92e722d8d23c26 and later · before 222b7005e4519f633b4cd666226256abbab46a1aaffected · git
    • 03149948832a078f759022ed5b92e722d8d23c26 and later · before c4a22154870813d10aa0b4c734a574c726f9d4b0affected · git
    • 03149948832a078f759022ed5b92e722d8d23c26 and later · before bb45f705c4440dd3c689328319b88dd28770bbb8affected · git
    • 03149948832a078f759022ed5b92e722d8d23c26 and later · before 0f63e656b1c679d32ac595de29d10c03efca6a25affected · git
    • before 5.19not affected · semver
    • 6.1.188 and later · up to and including 6.1.*not affected · semver
    • 6.6.157 and later · up to and including 6.6.*not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxall versions—
Debian:14linuxbefore 7.2.6-17.2.6-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

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    40Plan
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  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
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  • CVE-2026-74309vdpa/octeon_ep: fix IRQ-to-ring mapping in interrupt handler
    40Plan
  • CVE-2026-74280crypto: marvell/octeontx - fix DMA cleanup using wrong loop index
    40Plan
  • CVE-2026-74279crypto: cavium/cpt - fix DMA cleanup using wrong loop index
    40Plan

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux0f63e656b1c679d32ac595de29d10c03efca6a25Vendor (CNA)
Linux Linux220011fe95fc78b2bc2d7d43893bc73957a5c811Vendor (CNA)
Linux Linux222b7005e4519f633b4cd666226256abbab46a1aVendor (CNA)
Linux Linuxbb45f705c4440dd3c689328319b88dd28770bbb8Vendor (CNA)
Linux Linuxc4a22154870813d10aa0b4c734a574c726f9d4b0Vendor (CNA)
Linux Linuxc6875423ad849ac234ab9812eb72f37ff8a490b4Vendor (CNA)
Debian:linux7.2.6-1 · Debian:14Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

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Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

No CVSS vector for this record, so attack conditions can't be derived.

Weakness class (CWE)

—

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Noroxi analysis

No Noroxi analysis for this record yet

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Change log

  1. Fix✗ → ✓

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References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

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