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CVE-2026-79608

x86/AMD: ineffectual Zenbleed workaround

9.8 CriticalFix available

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

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
High

Exploit likelihood

0.34%Up 0.2 points since Oct 14, 2026
90%50%10%1%

What each source reports

CVE List Score used 9.8

x86/AMD: ineffectual Zenbleed workaround

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

Record
CVE-2026-79608
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-670
Updated
2026-11-02
EUVDEUVD-2026-98824 9.8

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

Record
EUVD-2026-98824
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
GitHub AdvisoriesGHSA-979q-v7jv-rjpg 9.8

The workaround for XSA-433 (Zenbleed, CVE-2023-20593) was later re-worked to better integrate...

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

Record
GHSA-979q-v7jv-rjpg
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-670
Updated
2026-11-02
NVD 9.8

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

Record
CVE-2026-79608
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-670
Updated
2026-11-02
OSVALPINE-CVE-2026-79608 9.8

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

Record
ALPINE-CVE-2026-79608
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVDEBIAN-CVE-2026-79608 9.8

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

Record
DEBIAN-CVE-2026-79608
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-04
OSVUBUNTU-CVE-2026-79608 9.8

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

Record
UBUNTU-CVE-2026-79608
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVopenSUSE-SU-2026:12138-1 No score

xen-4.22.0_06-1.1 on GA media

These are all security issues fixed in the xen-4.22.0_06-1.1 package on the GA media of openSUSE Tumbleweed.

Record
openSUSE-SU-2026:12138-1
Updated
2026-11-02
OSVSUSE-SU-2026:4942-1 No score

Security update for xen

This update for xen fixes the following issues:

  • CVE-2026-79608: x86/AMD: ineffectual Zenbleed workaround (bsc#1283317).
  • CVE-2026-79609: x86: XPTI may break on huge-memory systems (bsc#1283321).
  • CVE-2026-79610: grant-table: double version change race (bsc#1283322).
  • CVE-2026-79611: VMX: VMentry failure with branch tracing and blocked states (bsc#1283323).
  • CVE-2026-102700: gnttab: cache-flush handling may cause page reference leak (bsc#1283325).
Record
SUSE-SU-2026:4942-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
xen
Alpine:v3.21
 before 4.19.6-r2
4.19.6-r2
xen
Alpine:v3.22
 before 4.20.4-r2
4.20.4-r2
xen
Alpine:v3.23
 before 4.20.4-r2
4.20.4-r2
xen
Alpine:v3.24
 before 4.21.2-r2
4.21.2-r2
xen
Debian:13
 before 4.20.4+39-gf1e1321c87-0+deb13u1, plus listed versions
4.20.0+68-g35cb38b222-14.20.2+37-g61ff35323e-0+deb13u14.20.2+37-g61ff35323e-14.20.2+7-g1badcf5035-0+deb13u14.20.2+7-g1badcf5035-14.20.2+7-g1badcf5035-24.20.3+127-gc42374a105-0+deb13u14.20.3+127-gc42374a105-1
4.20.4+39-gf1e1321c87-0+deb13u1
xen
Debian:14
 before 4.20.4+39-gf1e1321c87-1, plus listed versions
4.20.0+68-g35cb38b222-14.20.2+37-g61ff35323e-14.20.2+7-g1badcf5035-14.20.2+7-g1badcf5035-24.20.3+127-gc42374a105-1
4.20.4+39-gf1e1321c87-1
xen
SUSE:Linux Enterprise Module for Basesystem 15 SP7
 before 4.20.4_06-150700.3.49.2
4.20.4_06-150700.3.49.2
xen
SUSE:Linux Enterprise Module for Server Applications 15 SP7
 before 4.20.4_06-150700.3.49.2
4.20.4_06-150700.3.49.2
xen
Ubuntu:16.04:LTS
 All versions, plus listed versions
4.5.1-0ubuntu14.5.1-0ubuntu24.6.0-1ubuntu14.6.0-1ubuntu24.6.0-1ubuntu4
Show 7 moreShow less
4.6.0-1ubuntu4.14.6.0-1ubuntu4.24.6.0-1ubuntu4.34.6.5-0ubuntu14.6.5-0ubuntu1.14.6.5-0ubuntu1.24.6.5-0ubuntu1.4
 None known
xen
Ubuntu:18.04:LTS
 All versions, plus listed versions
4.9.0-0ubuntu34.9.0-0ubuntu44.9.2-0ubuntu1
 None known
Show 6 moreShow less
Affected packages
PackageAffectedFixed
xen
Ubuntu:20.04:LTS
 All versions, plus listed versions
4.9.2-0ubuntu24.9.2-0ubuntu64.9.2-0ubuntu74.11.3+24-g14b62ab3e5-1ubuntu14.11.3+24-g14b62ab3e5-1ubuntu24.11.3+24-g14b62ab3e5-1ubuntu2.24.11.3+24-g14b62ab3e5-1ubuntu2.3
 None known
xen
Ubuntu:22.04:LTS
 All versions, plus listed versions
4.11.4+24-gddaaccbbab-1ubuntu24.16.0-1~ubuntu24.16.0-1~ubuntu2.1
 None known
xen
Ubuntu:24.04:LTS
 All versions, plus listed versions
4.17.2-14.17.2+55-g0b56bed864-14.17.2+76-ge1f9cb16e2-14.17.2+76-ge1f9cb16e2-1ubuntu14.17.3+10-g091466ba55-14.17.3+10-g091466ba55-1.1ubuntu24.17.3+10-g091466ba55-1.1ubuntu3
 None known
xen
Ubuntu:26.10
 All versions, plus listed versions
4.20.2+7-g1badcf5035-2build24.20.2+37-g61ff35323e-1ubuntu14.20.3+127-gc42374a105-1
 None known
xen
Ubuntu:26.04:LTS
 All versions, plus listed versions
4.20.0+68-g35cb38b222-14.20.2+7-g1badcf5035-24.20.2+7-g1badcf5035-2build2
 None known
xen
openSUSE:Tumbleweed
 before 4.22.0_06-1.1
4.22.0_06-1.1

History

History
RecordedChangedSources
affected, factsOSV
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-79608 is a critical vulnerability (CVSS 9.8) in Xen, published October 13, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.34%, the 27th percentile. Fixed in xen 4.19.6-r2.

References

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