8.8

CVE-2026-79609: x86: XPTI may break on huge-memory systems

Awaiting analysis
AliasesALPINE-CVE-2026-79609DEBIAN-CVE-2026-79609UBUNTU-CVE-2026-79609
Published 13-10-2026Last modified 20-10-2026

Vulnerability summary

CVE-2026-79609 is a high (CVSS 8.8) Improper Access Control vulnerability in xen. EPSS estimates a 0.11% chance of exploitation in the next 30 days, higher than 1.1% of scored vulnerabilities.

Priority
Routine

Not severe (CVSS 8.8, local access); no exploitation reported by the 5 checked sources

Source freshness unavailable

How is this decided?
CVSS score
8.8/10
010
High · v3.1 (CVE.org)
EPSS score
0.11%
0%100%
Low · Change unavailable
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 5 · Related 5
OPENSUSE-SU-2026:12138-1SUSE-SU-2026:4641-1SUSE-SU-2026:4642-1SUSE-SU-2026:4732-1SUSE-SU-2026:4942-1

Timeline

  1. 13-10-2026
    PublishedVulnerability first disclosed.
  2. 20-10-2026
    Last modifiedVulnerability information updated.

Description

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.

CVSS metrics

5 scores · 5 sources · 1 version

EPSS trend

Probability

0.11%

Chance of exploitation in the next 30 days

Percentile

1%

Versus all other CVEs

30-day change

Change unavailable

Change unavailable

14-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: local access, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.

Alpine1 product
  • xen< 4.19.6-r2 | < 4.20.4-r2 | < 4.21.2-r2
Debian1 product
  • xenAll versions (No fix recorded) | < 4.20.4+39-gf1e1321c87-0+deb13u1 | < 4.20.4+39-gf1e1321c87-1
Ubuntu1 product
  • xenAll versions (No fix recorded)

3 vendors · 3 products

References

6 links