CVE-2026-79609 (GCVE-0-2026-79609)

Vulnerability from cvelistv5 – Published: 2026-10-13 15:44 – Updated: 2026-10-20 17:34
VLAI
Title
x86: XPTI may break on huge-memory systems
Summary
XPTI (Xen Page Table Isolation) was introduced to mitigate Meltdown (CVE-2017-5754, one aspect of XSA-254). This involves copying 64-bit PV guest page table entries from guest-chosen root page tables to the Xen- chosen one which is in actual use by hardware. To read the guest root page table, the directmap is used. PV guests, however, have a directmap which may not cover all memory; in particular this is the case if any memory extends beyond the 5 TiB (CONFIG_BIGMEM=y: 3.5 TiB) address boundary.
Severity
8.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
SSVC
Exploitation: none Automatable: no Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-10-20 17:34 UTC
CWE
  • CWE-284 - Improper Access Control
Assigner
XEN CNA under the mitre root
CNA scorecard D 56/100 over 48 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Xen Xen Unknown: consult Xen advisory XSA-516
guessed Create a notification for this product.
Date Public
2026-10-13 12:00
Credits
This issue was discovered by George Dunlap.
Show details on NVD website
To clipboard 

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