Description
In the Linux kernel, the following vulnerability has been resolved:

KVM: x86: wean fast IN from emulator_pio_in

Use __emulator_pio_in() directly for fast PIO instead of bouncing through
emulator_pio_in() now that __emulator_pio_in() fills "val" when handling
in-kernel PIO. vcpu->arch.pio.count is guaranteed to be '0', so this a
pure nop.

emulator_pio_in_emulated is now the last caller of emulator_pio_in.

No functional change intended.
Published: 2026-07-30
Score: 5.5 Medium
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

Impact

The patch replaces a redundant call in the KVM x86 CPU emulator with a direct use of the low‑level __emulator_pio_in() function. The change is purely for performance and does not alter any functional or security‑relevant behavior. No new features or vulnerabilities are introduced.

Affected Systems

All Linux kernel builds that include the KVM hypervisor running in x86 mode. The modification applies to any host kernel that contains the described call path and therefore covers every Linux host running KVM in x86 emulation.

Risk and Exploitability

The EPSS score is less than 1% and the CVSS score is 5.5, indicating moderate severity; the vulnerability is not listed in the CISA KEV catalog and does not create a new attack surface. Consequently, there is no exploitable condition or realistic threat to existing deployments.

Generated by OpenCVE AI on August 4, 2026 at 11:47 UTC.

Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

  • Maintain current kernel updates to receive the fast PIO performance adjustment.
  • Employ standard KVM hardening practices, such as restricting VM access, disabling unused device emulation, and enabling audit logging for hypervisor operations.
  • Keep monitoring for any anomalous PIO activity, although no known security risk exists for this change.

Generated by OpenCVE AI on August 4, 2026 at 11:47 UTC.

Tracking

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Advisories

No advisories yet.

History

Mon, 03 Aug 2026 12:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-908
References
Metrics threat_severity

None

 cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Low

Thu, 30 Jul 2026 10:00:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: KVM: x86: wean fast IN from emulator_pio_in Use __emulator_pio_in() directly for fast PIO instead of bouncing through emulator_pio_in() now that __emulator_pio_in() fills "val" when handling in-kernel PIO. vcpu->arch.pio.count is guaranteed to be '0', so this a pure nop. emulator_pio_in_emulated is now the last caller of emulator_pio_in. No functional change intended.
Title KVM: x86: wean fast IN from emulator_pio_in
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Subscriptions

Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-07-30T09:18:06.591Z

Reserved: 2026-07-30T09:16:34.860Z

Link: CVE-2022-4994

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-07-30T10:16:34.270

Modified: 2026-07-30T10:16:34.270

Link: CVE-2022-4994

cve-icon Redhat

Severity : Low

Publid Date: 2026-07-30T00:00:00Z

Links: CVE-2022-4994 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-08-04T12:00:10Z

Weaknesses
  • CWE-908

    Use of Uninitialized Resource