Update your hypervisor before get bitten by venom

Posted on  5/13/2015

Security Researchers at CrowdStrike Discovered vulnerability in virtual floppy drive used by many virtualization platform like KVM and QEMU . flaw is presented since first ever code implemented for virtual floppy drive .

This vulnerability may allow an attacker to escape from the confines of an affected virtual machine (VM) guest and potentially obtain code-execution access to the host .

vulnerability details

The guest operating system communicates with the FDC by sending commands such as seek, read, write, format, etc. to the FDC’s input/output port. QEMU’s virtual FDC uses a fixed-size buffer for storing these commands and their associated data parameters. The FDC keeps track of how much data to expect for each command and, after all expected data for a given command is received from the guest system, the FDC executes the command and clears the buffer for the next command.

This buffer reset is performed immediately at the completion of processing for all FDC commands, except for two of the defined commands. An attacker can send these commands and specially crafted parameter data from the guest system to the FDC to overflow the data buffer and execute arbitrary code in the context of the host’s hypervisor process.

source :

How to fix

According to venom vulnerability information website , vendors released patches for affected products , just update and upgrade your system .
for Debian based systems

sudo apt-get update
sudo apt-get upgrade

for redhat and fedora

yum update
yum update qemu-kvm

affected Products

  • QEMU
  • KVM
  • Xen Hypervisors

Not Affected Products

  • VMware
  • Microsoft Hyper-V
  • Bochs hypervisors
  • Xen ARM systems are not vulnerable

More Information
Redhat Knowledge Base :
Redhat Bugzilla :

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