CVE-2023-34327 x86/AMD: Debug Mask handling
A flaw in Xen's handling of AMD debug masks allows a guest vCPU to cause a denial of service by operating in an incorrect debug state.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2023-34327?
CVE-2023-34327 is a medium-severity denial of service vulnerability in Xen Xen, published on 5 Jan 2024. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
[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.
Which versions are affected by CVE-2023-34327?
It affects 1 product.
Products include Xen Xen.
How do I fix CVE-2023-34327?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2023-34327 being exploited?
There is no known exploitation of CVE-2023-34327 in the wild and no public exploit code.
Other vulnerabilities in Xen Xen
Sources
Also known as ALPINE-CVE-2023-34327, DEBIAN-CVE-2023-34327, GHSA-7fx2-c8rv-2w4f, UBUNTU-CVE-2023-34327.