CVE-2021-20196 Explained : Impact and Mitigation
Learn about CVE-2021-20196, a NULL pointer dereference flaw in QEMU's floppy disk emulator allowing a privileged guest user to crash the QEMU process, impacting system availability. Find out about affected versions, exploitation, and mitigation strategies.
A NULL pointer dereference flaw was found in the floppy disk emulator of QEMU, allowing a privileged guest user to crash the QEMU process on the host, resulting in a denial of service. This vulnerability, tracked as CWE-476, affects versions up to (including) QEMU 5.2.0.
Understanding CVE-2021-20196
This section provides insights into the nature and impact of CVE-2021-20196.
What is CVE-2021-20196?
The vulnerability identified as CVE-2021-20196 is a NULL pointer dereference flaw in QEMU's floppy disk emulator. It occurs during read/write ioport commands processing when the selected floppy drive is not initialized with a block device. This flaw enables a privileged guest user to crash the QEMU process on the host, leading to a denial of service.
The Impact of CVE-2021-20196
The highest risk posed by CVE-2021-20196 is to system availability, as it allows an attacker to disrupt the normal functioning of the host by causing the QEMU process to crash.
Technical Details of CVE-2021-20196
Explore the specific technical aspects of CVE-2021-20196 to understand the vulnerability further.
Vulnerability Description
The vulnerability stems from a NULL pointer dereference issue in the floppy disk emulator of QEMU, triggered by unhandled read/write ioport commands without the necessary initialization.
Affected Systems and Versions
CVE-2021-20196 affects QEMU versions up to (including) 5.2.0, making systems with these versions vulnerable to exploitation.
Exploitation Mechanism
Exploiting this vulnerability requires a privileged guest user to send malicious read/write ioport commands to an uninitialized floppy drive, leading to a crash in the QEMU process.
Mitigation and Prevention
Learn about the measures you can take to mitigate the risks associated with CVE-2021-20196.
Immediate Steps to Take
Consider immediate actions to secure your systems against potential exploitation of CVE-2021-20196, including monitoring for security updates and patches.
Long-Term Security Practices
Implementing robust security practices such as regular software updates, access control, and network segmentation can help prevent such vulnerabilities in the long term.
Patching and Updates
Stay informed about security advisories and updates from QEMU and relevant vendors to apply patches promptly and ensure your systems are protected against CVE-2021-20196.