CVE-2024-50115: KVM: nSVM: Ignore nCR3[4:0] when loading PDPTEs from memory

Severity: high (CVSS 7.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-11-05 · updated 2026-08-04
Weakness: CWE-125

Description

In the Linux kernel, the following vulnerability has been resolved: KVM: nSVM: Ignore nCR3[4:0] when loading PDPTEs from memory Ignore nCR3[4:0] when loading PDPTEs from memory for nested SVM, as bits 4:0 of CR3 are ignored when PAE paging is used, and thus VMRUN doesn't enforce 32-byte alignment of nCR3. In the absolute worst case scenario, failure to ignore bits 4:0 can result in an out-of-bounds read, e.g. if the target page is at the end of a memslot, and the VMM isn't using guard pages. Per the APM: The CR3 register points to the base address of the page-directory-pointer table. The page-directory-pointer table is aligned on a 32-byte boundary, with the low 5 address bits 4:0 assumed to be 0. And the SDM's much more explicit: 4:0 Ignored Note, KVM gets this right when loading PDPTRs, it's only the nSVM flow that is broken.

Affected products

Linux kernel: from 3.2 before 5.10.229; from 5.11 before 5.15.170; from 5.16 before 6.1.115; from 6.2 before 6.6.59; from 6.7 before 6.11.6; 6.12-rc1, 6.12-rc2, 6.12-rc3, 6.12-rc4 — fixed in 5.10.229, 5.15.170, 6.1.115, 6.11.6, 6.6.59

How to fix

Upgrade to a fixed version: Linux kernel 5.10.229, 5.15.170, 6.1.115, 6.11.6. Check the vendor advisory for mitigations.

References

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