Critical Race Condition Vulnerability in Xen Package Leading to Potential Host OS Denial of Service
Summary
ALPINE-CVE-2020-27672: An issue was discovered in Xen through 4.14.x allowing x86 guest OS users to cause a host OS denial of service, achieve data corruption, or possibly gain privileges by exploiting a race condition that leads to a use-afte... Affects xen versions < 4.12.4-r0. Fixed in 4.12.4-r0. How to fix ↓
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Background
Xen is an open-source hypervisor that enables the creation and management of virtual machines. It is widely used for server virtualization and cloud computing. The Xen package allows multiple operating systems to run concurrently on a single physical machine, providing isolation and resource management. However, it is susceptible to vulnerabilities that can compromise the host OS's stability and security.
Vulnerability Detail
An issue was discovered in Xen through version 4.14.x, which allows x86 guest OS users to exploit a race condition. This vulnerability can lead to a denial of service on the host OS, data corruption, or even privilege escalation. The root cause lies in a use-after-free condition involving 2MiB and 1GiB superpages, which can be triggered by malicious guest OS users.
How To Fix
Minimum fixed version
4.12.4-r0
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
As a temporary workaround, consider isolating the affected virtual machines or limiting their access to critical resources until the package can be updated. Additionally, monitor the system for any unusual behavior that may indicate exploitation of this vulnerability.
Conclusion
The Xen package is critical for virtualization, but it has a significant vulnerability that can lead to severe consequences if exploited. It is essential to update to the patched versions to ensure the security and stability of the host OS. Utilizing tools like Vulert can help in monitoring and managing vulnerabilities effectively.
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FAQ
The CVSS score of this vulnerability is 7.0, indicating a high severity level.
You can use Vulert to monitor and alert for open-source vulnerabilities in your software. Visit Vulert Scanner to check if your application is affected without requiring any signup.
Exploitation of this vulnerability can lead to denial of service, data corruption, or privilege escalation on the host OS.
Yes, updating to version 4.12.4-r0 or later for Alpine v3.10, or 4.13.2-r0 for Alpine v3.11 and v3.12, or 4.14.0-r2 for Alpine v3.13 and later will mitigate the risk.
If immediate updates are not possible, consider isolating affected virtual machines and monitoring for unusual behavior as a temporary measure.
References
Related vulnerabilities
Recent vulnerabilities recorded for xen.
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