Denial of Service Vulnerability in Xen Package: CVE-2020-11743
Summary
ALPINE-CVE-2020-11743: An issue was discovered in Xen through 4.13.x, allowing guest OS users to cause a denial of service because of a bad error path in GNTTABOP_map_grant. Affects xen versions < 4.12.2-r1. Fixed in 4.12.2-r1. How to fix ↓
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Background
Xen is an open-source hypervisor that allows multiple operating systems to run concurrently on a single physical machine. It provides virtualization services for various operating systems, enabling efficient resource management and isolation. The Xen package is widely used in cloud computing and server environments. However, it is susceptible to vulnerabilities that can compromise the stability and security of the host and guest operating systems.
Vulnerability Detail
An issue was discovered in Xen through version 4.13.x, which allows guest OS users to cause a denial of service due to a flawed error handling path in the GNTTABOP_map_grant operation. The grant table operations are expected to return 0 for success and a negative number for errors. However, misplaced brackets in the code cause one error path to return 1 instead of a negative value. This misbehavior leads the grant table code in Linux to treat the condition as a success, resulting in an incorrectly initialized state. A malicious or buggy guest can exploit this vulnerability, causing a crash in the Linux-based dom0 or backend domain.
How To Fix
Minimum fixed version
4.12.2-r1
This is the first release that contains the fix.
sudo apk add --upgrade xenTip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
If immediate patching is not feasible, consider isolating the affected guest OS or limiting its permissions to reduce the risk of exploitation. Additionally, monitor the system logs for unusual activity that may indicate an attempted exploit.
Conclusion
CVE-2020-11743 is a significant vulnerability in the Xen hypervisor that can lead to denial of service attacks. It is crucial to update to the patched versions of the Xen package to ensure the security and stability of your systems. Regular monitoring and using tools like Vulert can help maintain awareness of vulnerabilities in your software.
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FAQ
CVE-2020-11743 is a vulnerability in the Xen hypervisor that allows guest OS users to cause a denial of service due to improper error handling in grant table operations.
You can use Vulert's playground at Vulert Scanner to check if your application is affected by this vulnerability without needing to sign up.
Exploitation of this vulnerability can lead to a denial of service, causing the host or backend domain to crash, which can disrupt services and affect availability.
The CVSS score of CVE-2020-11743 is 5.5, indicating a moderate severity level.
You can mitigate the risk by isolating the affected guest OS, limiting its permissions, and monitoring system logs for any unusual activity.
References
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