CVE-2026-43045: mshv: Fix error handling in mshv_region_pin

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-05-01 · updated 2026-10-15

Description

In the Linux kernel, the following vulnerability has been resolved: mshv: Fix error handling in mshv_region_pin The current error handling has two issues: First, pin_user_pages_fast() can return a short pin count (less than requested but greater than zero) when it cannot pin all requested pages. This is treated as success, leading to partially pinned regions being used, which causes memory corruption. Second, when an error occurs mid-loop, already pinned pages from the current batch are not properly accounted for before calling mshv_region_invalidate_pages(), causing a page reference leak. Treat short pins as errors and fix partial batch accounting before cleanup.

Affected products

Linux kernel: from 6.15 before 6.19.12; 7.0-rc1, 7.0-rc2, 7.0-rc3, 7.0-rc4 — fixed in 6.19.12

How to fix

Upgrade to a fixed version: Linux kernel 6.19.12. Check the vendor advisory for mitigations.

References

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