Insufficient Care with Non-Coherent Mappings in Xen
Summary
CVE-2022-26364: x86 pv: Insufficient care with non-coherent mappings T[his CNA information record relates to multiple CVEs; the text explains which aspects/vulnerabilities correspond to which CVE.] Xen maintains a type reference count f... Affects xen versions < 4.14.5-r1. Fixed in 4.14.5-r1. How to fix ↓
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Background
Xen is an open-source hypervisor that provides virtualization capabilities for various operating systems. It allows multiple guest operating systems to run on a single host machine, providing isolation and resource management. The Xen package in Alpine Linux versions 3.13 to 3.18 is affected by a vulnerability that arises from insufficient care with non-coherent mappings in x86 PV (Paravirtualized) guests. This vulnerability can lead to incorrect conclusions about the safety of page contents, potentially allowing PV guests to have direct writable access to pagetables without proper auditing by Xen.
Vulnerability Detail
The vulnerability in Xen arises from a flaw in its safety logic, which fails to account for CPU-induced cache non-coherency. In certain cases, the CPU can cause the content of the cache to differ from the content in main memory. This discrepancy can lead to Xen incorrectly determining that the contents of a page are safe, even when they may not be. As a result, PV guests may gain unauthorized write access to pagetables, bypassing the intended safety measures. This vulnerability has a CVSS score of 6.7, indicating a medium severity level.
How To Fix
Minimum fixed version
4.14.5-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
There is no known workaround for this vulnerability at this time.
Conclusion
The vulnerability in Xen that allows PV guests to gain unauthorized write access to pagetables can be mitigated by updating the Xen package to the fixed versions. It is recommended to promptly apply the necessary updates to ensure the security and integrity of the system. For further support on vulnerability remediation, please contact DevNack.com.
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FAQ
Xen is an open-source hypervisor that provides virtualization capabilities for various operating systems. It allows multiple guest operating systems to run on a single host machine, providing isolation and resource management.
Alpine Linux versions 3.13 to 3.18 are affected by this vulnerability.
This vulnerability can allow PV guests in Xen to gain unauthorized write access to pagetables, bypassing the intended safety measures.
The CVSS score of this vulnerability is 6.7, indicating a medium severity level.
To fix this vulnerability, update the Xen package to the fixed versions: 4.15.2-r1 for Alpine Linux versions 3.13 and 3.14, and 4.16.1-r1 for Alpine Linux versions 3.15 to 3.18.
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