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Fencer Vulns
critical 9.8

CVE-2026-79608 json

x86/AMD: ineffectual Zenbleed workaround

published 2026-10-13 26 d ago modified 2026-10-20 19 d ago also EUVD-2026-98824

cvss
9.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 27%
public exploits
0
none known

Summary

The workaround for XSA-433 (Zenbleed, CVE-2023-20593) was later re-worked to better integrate with other manipulations of the same MSR. In this rework an inverted conditional was introduced, resulting in the workaround to not be applied when needed and vice versa.

For more details, see: http://xenbits.xen.org/xsa/advisory-433.html

Patch / fix

  • xen Debian 13 4.20.4+39-gf1e1321c87-0+deb13u1
  • xen Debian 14 4.20.4+39-gf1e1321c87-1

debian advisories DEBIAN-CVE-2026-79608

  • xen SLE Module for Server Applications 15 SP7, SLE Module for Basesystem 15 SP7 4.20.4_06-150700.3.49.2

suse advisories SUSE-SU-2026:4942-1

  • xen openSUSE Tumbleweed 4.22.0_06-1.1

opensuse advisories openSUSE-SU-2026:12138-1

  • xen Alpine 3.21 4.19.6-r2
  • xen Alpine 3.23, Alpine 3.22 4.20.4-r2
  • xen Alpine 3.24 4.21.2-r2

alpine advisories ALPINE-CVE-2026-79608

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-79608 updated cvss 6.5

xen: xen: Information disclosure via inverted conditional in Zenbleed workaround

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
total
Assessed
19 d ago

Exploit prediction

0.34% chance of exploitation in the next 30 days, higher than 27% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Xen Xen

Classification

Weakness
  • CWE-670 Always-Incorrect Control Flow Implementation

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.