Critical Vulnerability in linux-lts and xen Packages: Potential Privilege Escalation and Information Leak
Summary
ALPINE-CVE-2020-29569: An issue was discovered in the Linux kernel through 5.10.1, as used with Xen through 4.14.x. Affects linux-lts versions < 5.10.4-r0. Fixed in 5.10.4-r0. How to fix ↓
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Background
The linux-lts package is a long-term support version of the Linux kernel, providing stability and security for various applications. It is widely used in server environments and embedded systems. The xen package is a hypervisor that allows multiple operating systems to run concurrently on a host machine. Both packages are crucial for system performance and security, but they are vulnerable to a specific issue that can lead to severe consequences.
Vulnerability Detail
An issue was discovered in the Linux kernel through version 5.10.1, as used with Xen through version 4.14.x. The vulnerability arises from the PV block backend, which expects the kernel thread handler to reset a specific pointer when stopped. If the frontend rapidly toggles between connect and disconnect states, the handler may not execute in time, leading to the potential reuse of a freed pointer. This situation can cause a crash in the domain zero (dom0) and may allow privilege escalation and information leaks, particularly affecting systems utilizing the Linux blkback.
How To Fix
Minimum fixed version
5.10.4-r0
This is the first release that contains the fix.
sudo apk add --upgrade linux-ltsTip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary measure, you can limit the toggling of the block frontend states or implement additional monitoring to detect rapid state changes. However, the best course of action is to apply the patch as soon as possible.
Conclusion
The vulnerability in the linux-lts and xen packages poses significant risks, including potential privilege escalation and information leaks. It is crucial to update to the patched version 5.10.4-r0 to secure your systems. Additionally, utilizing tools like Vulert can help monitor and alert for open-source vulnerabilities in real-time.
See every vulnerability recorded for linux-lts →
FAQ
The CVSS score of this vulnerability is 8.8, indicating a high severity level.
All versions of linux-lts prior to 5.10.4-r0 are affected by this vulnerability.
Yes, this vulnerability can potentially lead to privilege escalation and information leaks, which may result in data loss.
You can use Vulert's playground at Vulert Scanner to check if your application is affected by this vulnerability without needing to sign up.
If you cannot apply the patch immediately, consider implementing temporary workarounds such as limiting the toggling of block frontend states.
References
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