CVE-2023-34328

Summary

[This CNA information record relates to multiple CVEs; the text explains which aspects/vulnerabilities correspond to which CVE.]

AMD CPUs since ~2014 have extensions to normal x86 debugging functionality. Xen supports guests using these extensions.

Unfortunately there are errors in Xen's handling of the guest state, leading to denials of service.

1. CVE-2023-34327 - An HVM vCPU can end up operating in the context of a previous vCPUs debug mask state.

2. CVE-2023-34328 - A PV vCPU can place a breakpoint over the live GDT. This allows the PV vCPU to exploit XSA-156 / CVE-2015-8104 and lock up the CPU entirely.

Affected Software

Weaknesses

Workarounds

For CVE-2023-34327, HVM VMs which can see the DBEXT feature are not susceptible to running in the wrong state. By default, VMs will see the DBEXT feature on capable hardware, and when not explicitly levelled for migration compatibility.

For CVE-2023-34328, PV VMs which cannot see the DBEXT feature cannot leverage the vulnerability.

ADP Enrichment

CVE Program Container

Additional References

• https://xenbits.xenproject.org/xsa/advisory-444.html
• http://xenbits.xen.org/xsa/advisory-444.html

CISA ADP Vulnrichment

• SSVC:
• Exploitation: none
  • Automatable: no
  • Technical Impact: partial

References

• https://xenbits.xenproject.org/xsa/advisory-444.html

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