x86: XPTI may break on huge-memory systems
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.
CVE-2026-79609
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-79609
Xen
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"vendor": "Xen",
"product": "Xen",
"versions": [
{
"status": "unknown",
"version": "consult Xen advisory XSA-516"
}
],
"defaultStatus": "unknown"
}
]- Related CVEs
- CVE-2026-79609
Source reference:
/cveMetadata/cveId
Publisher severity
No explicit severity was provided.
- Event
- #42421 · Revision 1
- Added to Heist Feed
- Publisher date