CVE-2019-19578 Details

CVE-2019-19578

Published: 2019-12-11
Last Modified: 2020-08-24
CVE Author: NIST National Vulnerability Database
CVE Assigner: cve@mitre.org
Summary

An issue was discovered in Xen through 4.12.x allowing x86 PV guest OS users to cause a denial of service via degenerate chains of linear pagetables, because of an incorrect fix for CVE-2017-15595. "Linear pagetables" is a technique which involves either pointing a pagetable at itself, or to another pagetable of the same or higher level. Xen has limited support for linear pagetables: A page may either point to itself, or point to another pagetable of the same level (i.e., L2 to L2, L3 to L3, and so on). XSA-240 introduced an additional restriction that limited the "depth" of such chains by allowing pages to either *point to* other pages of the same level, or *be pointed to* by other pages of the same level, but not both. To implement this, we keep track of the number of outstanding times a page points to or is pointed to another page table, to prevent both from happening at the same time. Unfortunately, the original commit introducing this reset this count when resuming validation of a partially-validated pagetable, incorrectly dropping some "linear_pt_entry" counts. If an attacker could engineer such a situation to occur, they might be able to make loops or other arbitrary chains of linear pagetables, as described in XSA-240. A malicious or buggy PV guest may cause the hypervisor to crash, resulting in Denial of Service (DoS) affecting the entire host. Privilege escalation and information leaks cannot be excluded. All versions of Xen are vulnerable. Only x86 systems are affected. Arm systems are not affected. Only x86 PV guests can leverage the vulnerability. x86 HVM and PVH guests cannot leverage the vulnerability. Only systems which have enabled linear pagetables are vulnerable. Systems which have disabled linear pagetables, either by selecting CONFIG_PV_LINEAR_PT=n when building the hypervisor, or adding pv-linear-pt=false on the command-line, are not vulnerable.

Analysis
Common Vulnerability Score System v2.0
Severity High
Base Score 7.2/10
Exploit Score 3.9/10
Access Vector Local
Access Complexity Low
Authentication None
Impact Score 10/10
Confidentiality Impact Complete
Availability Impact Complete
Integrity Impact Complete
Vector String AV:L/AC:L/Au:N/C:C/I:C/A:C
Common Vulnerability Score System v3.1
Severity High
Base Score 8.8/10
Exploit Score 2/10
Access Vector Local
Access Complexity Low
Privileges Required Low
Impact Score 6/10
Confidentiality Impact High
Availability Impact High
Integrity Impact High
Scope Changed
User Interaction None
Vector String CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Products Reported
CPE Vulnerable Start Excluding
cpe:2.3:o:xen:xen:*:*:*:*:*:*:x86:* Yes - -
cpe:2.3:o:fedoraproject:fedora:31:*:*:*:*:*:*:* Yes - -
References

https://xenbits.xen.org/xsa/advisory-309.html
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/m
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/m
http://lists.opensuse.org/opensuse-security-announce/2020-01/msg00011.html
https://www.debian.org/security/2020/dsa-4602
https://seclists.org/bugtraq/2020/Jan/21
https://security.gentoo.org/glsa/202003-56

CVE ID
CVE-2019-19578
Published
2019-12-11
Modified
2020-08-24
CVSSv2.0
High
CVSSv3.1
High
PCI Compliance
Fail
US-CERT Alert
No
CWE
CWE-682

Free Vulnerability Scanning, Assessment and Management

Mageni's Platform is packed with all the features you need to scan, assess and manage vulnerabilities like this - it is free, open source, lightning fast, reliable and scalable.

Router
Servers
Laptop
Database
Group
Cloud

Frequently Asked Questions

No, you can scan concurrently as many assets as you want. Please note that you must be aware of the hardware requeriments of the platform to ensure a good performance.

No, you can add as many assest as you want. It doesn't matters if you have millions of assets, we won't charge you for that.

No. The software is completely free. We have no intention to charge you to use the software, in fact - it completely goes against our beliefs and business model.

A vulnerability is defined in the ISO 27002 standard as “A weakness of an asset or group of assets that can be exploited by one or more threats” (International Organization for Standardization, 2005)

We generate revenue by providing support and other services for customers that require a subscription so they get guaranteed support and enterprise services. To use Mageni's Platform is completely free, with no limits at all.

Yes. Mageni understands that there are professionals and businesses that need commercial support so Mageni provides an active support subscription with everything needed to run Mageni's Platform reliably and securely. More than software, it's access to security experts, knowledge resources, security updates, and support tools you can't get anywhere else. The subscription includes:

  • Ongoing delivery
    • Patches
    • Bug fixes
    • Updates
    • Upgrades
  • Technical support
    • 24/7 availability
    • Unlimited Incidents
    • Specialty-based routing
    • Multi-Channel
  • Commitments
    • Software certifications
    • Software assurance
    • SLA

No, we don't store the information of your vulnerabilities in our servers.

Vulnerability management is the process in which vulnerabilities in IT are identified and the risks of these vulnerabilities are evaluated. This evaluation leads to correcting the vulnerabilities and removing the risk or a formal risk acceptance by the management of an organization. The term vulnerability management is often confused with vulnerability scanning. Despite the fact both are related, there is an important difference between the two. Vulnerability scanning consists of using a computer program to identify vulnerabilities in networks, computer infrastructure or applications. Vulnerability management is the process surrounding vulnerability scanning, also taking into account other aspects such as risk acceptance, remediation etc. Source: "Implementing a Vulnerability Management Process". SANS Institute.

I am ready to start scanning for vulnerabilities