Bug 851139 (CVE-2012-3494)

Summary: CVE-2012-3494 kernel: xen: hypercall set_debugreg vulnerability
Product: [Other] Security Response Reporter: Petr Matousek <pmatouse>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED NOTABUG QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: drjones, lersek, pbonzini, security-response-team, tburke
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2019-06-10 10:59:07 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Bug Depends On: 854585    
Bug Blocks: 851204    

Description Petr Matousek 2012-08-23 10:33:56 UTC
set_debugreg allows writes to reserved bits of the DR7 debug control register on x86-64.
A malicious guest can cause the host to crash, leading to a DoS.
If the vulnerable hypervisor is run on future hardware, the impact of the vulnerability might be widened depending on the future assignment of the currently-reserved debug register bits.

All systems running 64-bit paravirtualised guests are vulnerable to this issue.


Red Hat would like to thank the Xen project for reporting this issue.

Comment 3 Petr Matousek 2012-08-23 11:29:41 UTC

Not vulnerable.

This issue did not affect the versions of the kernel-xen package as shipped with Red Hat Enterprise Linux 5.

This issue did not affect Red Hat Enterprise Linux 6 and Red Hat Enterprise MRG as we did not have support for Xen hypervisor.

Comment 4 Petr Matousek 2012-09-05 11:38:39 UTC
Now public via:


Comment 5 Petr Matousek 2012-09-05 11:40:03 UTC
Created xen tracking bugs for this issue

Affects: fedora-all [bug 854585]

Comment 6 Fedora Update System 2012-09-17 17:59:46 UTC
xen-4.1.3-2.fc16 has been pushed to the Fedora 16 stable repository.  If problems still persist, please make note of it in this bug report.