CVE-2019-18421
7.5 · HIGHOverview
CVE-2019-18421 is a high-severity vulnerability affecting xen xen. It was published on October 31, 2019 and has a CVSS 3.1 base score of 7.5 (HIGH).
This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. Some level of privileges is required for exploitation.
Technical Description
An issue was discovered in Xen through 4.12.x allowing x86 PV guest OS users to gain host OS privileges by leveraging race conditions in pagetable promotion and demotion operations. There are issues with restartable PV type change operations. To avoid using shadow pagetables for PV guests, Xen exposes the actual hardware pagetables to the guest. In order to prevent the guest from modifying these page tables directly, Xen keeps track of how pages are used using a type system; pages must be "promoted" before being used as a pagetable, and "demoted" before being used for any other type. Xen also allows for "recursive" promotions: i.e., an operating system promoting a page to an L4 pagetable may end up causing pages to be promoted to L3s, which may in turn cause pages to be promoted to L2s, and so on. These operations may take an arbitrarily large amount of time, and so must be re-startable. Unfortunately, making recursive pagetable promotion and demotion operations restartable is incredib
Remediation
Check the references section for vendor advisories and patches from xen. Update xen to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| xen | xen | 0 | Affected |
References
Frequently Asked Questions
What is CVE-2019-18421?
CVE-2019-18421 is a high-severity vulnerability affecting xen xen. It was published on October 31, 2019 and has a CVSS 3.1 base score of 7.5 (HIGH).
How severe is CVE-2019-18421?
This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. Some level of privileges is required for exploitation.
How do I fix or remediate CVE-2019-18421?
Check the references section for vendor advisories and patches from xen. Update xen to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2019-18421?
CyberStrike's AI-powered security agents can automatically detect CVE-2019-18421 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
AI agents map your attack surface to find vulnerabilities like this one.
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