CVE-2019-19583 – This CVE allows x86 HVM/PVH guest OS users in X... (How to Fix)

Q: What is the severity of CVE-2019-19583?

CVE-2019-19583 has a CVSS score of 7.5 (HIGH). This CVE allows x86 HVM/PVH guest OS users in Xen hypervisors to cause a denial of service by crashing the guest OS through a VMX VMEntry check failure. Only systems with Intel, Cyrix, or Zhaoxin CPUs running HVM/PVH guests are affected. Arm, AMD systems, and PV guests are not vulnerable.

📋 TL;DR

This CVE allows x86 HVM/PVH guest OS users in Xen hypervisors to cause a denial of service by crashing the guest OS through a VMX VMEntry check failure. Only systems with Intel, Cyrix, or Zhaoxin CPUs running HVM/PVH guests are affected. Arm, AMD systems, and PV guests are not vulnerable.

💻 Affected Systems

Products:

Xen hypervisor

Versions: All versions through 4.12.x

Operating Systems: Any OS running Xen hypervisor

Default Config Vulnerable: ⚠️ Yes

Notes: Only affects x86 systems with VMX hardware virtual extensions (Intel, Cyrix, Zhaoxin CPUs). HVM/PVH guest types only. Not applicable to Arm, AMD, or PV guests.

📦 What is this software?

⚠️ Risk & Real-World Impact

🔴

Worst Case

Guest OS crash leading to denial of service for that virtual machine

🟠

Likely Case

Guest OS crash requiring restart of the affected virtual machine

🟢

If Mitigated

No impact if patched or using unaffected CPU architectures

🌐 Internet-Facing: LOW - Requires guest OS user access, not directly network exploitable

🏢 Internal Only: MEDIUM - Malicious or compromised guest users could crash their VMs

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Requires guest OS user privileges and specific CPU state conditions (#DB intercepted, Single Stepping active, blocked by STI/MovSS active)

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Patched in Xen security updates (see XSA-260)

Vendor Advisory: https://xenbits.xen.org/xsa/advisory-260.html

Restart Required: Yes

Instructions:

1. Update Xen hypervisor to patched version. 2. Reboot hypervisor host. 3. Restart affected VMs.

🔧 Temporary Workarounds

Migrate to PV guests

all

Convert affected HVM/PVH guests to PV mode if possible

Use AMD or Arm hardware

all

Deploy on unaffected CPU architectures

🧯 If You Can't Patch

Restrict guest user privileges to minimize attack surface
Monitor for guest OS crashes and investigate suspicious activity

🔍 How to Verify

Check if Vulnerable:

Check Xen version and CPU type: 'xl info' and 'cat /proc/cpuinfo'

Check Version:

xl info | grep xen_version

Verify Fix Applied:

Verify Xen version is updated and check for XSA-260 patch in changelog

📡 Detection & Monitoring

Log Indicators:

Guest OS crash logs
Xen hypervisor error messages related to VMEntry failures

Network Indicators:

Sudden loss of connectivity to guest VM

SIEM Query:

Search for: 'guest crash' OR 'VMEntry failure' OR 'Xen error' in hypervisor logs

📊 Metadata

CVE ID: CVE-2019-19583

CVSS v3 Score: 7.5 (HIGH)

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Published: December 11, 2019

Last Updated: November 21, 2024

🔗 References

http://lists.opensuse.org/opensuse-security-announce/2020-01/msg00011.html Mailing List,Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/34HBFTYNMQMWIO2GGK7DB6KV4M6R5YPV/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/D5R73AYE53QA32KTMHUVKCX6E52CIS43/
https://seclists.org/bugtraq/2020/Jan/21 Mailing List,Third Party Advisory
https://security.gentoo.org/glsa/202003-56 Third Party Advisory
https://www.debian.org/security/2020/dsa-4602 Third Party Advisory
https://xenbits.xen.org/xsa/advisory-308.html Patch,Vendor Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-01/msg00011.html Mailing List,Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/34HBFTYNMQMWIO2GGK7DB6KV4M6R5YPV/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/D5R73AYE53QA32KTMHUVKCX6E52CIS43/
https://seclists.org/bugtraq/2020/Jan/21 Mailing List,Third Party Advisory
https://security.gentoo.org/glsa/202003-56 Third Party Advisory
https://www.debian.org/security/2020/dsa-4602 Third Party Advisory
https://xenbits.xen.org/xsa/advisory-308.html Patch,Vendor Advisory

📤 Share & Export

📄 Export Markdown 📋 Export JSON