Read the docs
TI-2026-71802 Aliases CVE-2026-79608GHSA-979q-v7jv-rjpg

Ineffective Zenbleed workaround in Xen on AMD x86 systems

Priority MEDIUM 49CWE-670Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
High · High · High
Fix status
No fix listed

Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA.

Summary

Xen on AMD x86 systems is affected by an ineffective workaround for the Zenbleed issue. A later rework of the workaround introduced an inverted conditional (CWE-670), so the workaround is skipped when it is needed and applied when it is not. An attacker with network access and no privileges or user interaction could cause a high impact on confidentiality, integrity and availability.

Written with Claude Haiku 5.5 from the sources below · 2026-10-27

Description from the CNA

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

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00336 27th percentileScored 2026-11-07
Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
XenXen——No fix listedCNA
  • Xen VendorXen Affected — Fixed in — No fix listed CNA

Remediation

The sources list no fixed version for Xen.

Written with Claude Haiku 5.5 from the sources below · 2026-10-27

Vendor assessments

Red Hat

Red Hat's page for this CVE →

Not affected: 1 product
  • Red Hat

Timeline

  1. 2026-10-13 Threatist record created from CVE-2026-79608
  2. 2026-10-13 Alias added: GHSA-979q-v7jv-rjpg
  3. 2026-10-20 CVSS score added · CISA ADP
  4. 2026-10-20 Weakness changed · CISA ADP
  5. 2026-10-20 CISA SSVC decision points changed
  6. 2026-10-20 Priority changed: LOW → MEDIUM
  7. 2026-10-23 Affected versions changed · Red Hat
  8. 2026-10-23 CVSS score added · Red Hat

References

Other 1

  • TI-2012-00210 The x86-64 kernel system-call functionality in Xen 4.1.2 and earlier, as used in Citrix… CVSS 2.0HIGH 7.2
  • TI-2023-07042 Information disclosure through error messages in AMD Ryzen™ 3000 Series Desktop… CVSS 3.1MEDIUM 5.5
  • TI-2015-04333 The C+ mode offload emulation in the RTL8139 network card device model in QEMU, as used… CVSS 2.0HIGH 9.3
  • TI-2015-06741 The KVM subsystem in the Linux kernel through 4.2.6, and Xen 4.3.x through 4.6.x, allows… CVSS 3.1CRITICAL 10.0
  • TI-2018-06436 A statement in the System Programming Guide of the Intel 64 and IA-32 Architectures… CVSS 3.0HIGH 7.8
  • TI-2024-20522 x86: Incorrect logic for BTC/SRSO mitigations CVSS 3.1HIGH 7.5
See all 541 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences