CVE-2019-18389 – A heap-based buffer overflow in virglrenderer's... (How to Fix)

Q: What is the severity of CVE-2019-18389?

CVE-2019-18389 has a CVSS score of 7.8 (HIGH). A heap-based buffer overflow in virglrenderer's vrend_renderer_transfer_write_iov function allows guest OS users to cause denial of service or potentially achieve QEMU guest-to-host escape and code execution. This affects virtualization environments using virglrenderer through version 0.8.0 for 3D acceleration in virtual machines.

📋 TL;DR

A heap-based buffer overflow in virglrenderer's vrend_renderer_transfer_write_iov function allows guest OS users to cause denial of service or potentially achieve QEMU guest-to-host escape and code execution. This affects virtualization environments using virglrenderer through version 0.8.0 for 3D acceleration in virtual machines.

💻 Affected Systems

Products:

virglrenderer
QEMU with virglrenderer integration
Virtualization platforms using virglrenderer

Versions: virglrenderer through version 0.8.0

Operating Systems: Linux hosts running QEMU/KVM with virglrenderer, Guest OSes with virglrenderer 3D acceleration

Default Config Vulnerable: ⚠️ Yes

Notes: Requires virglrenderer 3D acceleration to be enabled for guest VMs. Not all QEMU configurations use virglrenderer.

📦 What is this software?

⚠️ Risk & Real-World Impact

🔴

Worst Case

Full guest-to-host escape leading to arbitrary code execution on the hypervisor/host system, potentially compromising all VMs and host resources.

🟠

Likely Case

Denial of service causing VM crashes or instability, with potential for limited guest-to-host escape in targeted attacks.

🟢

If Mitigated

Isolated VM crash without host compromise if proper virtualization isolation controls are effective.

🌐 Internet-Facing: LOW - This vulnerability requires access to a guest VM, not directly internet-exposed services.

🏢 Internal Only: HIGH - In virtualized environments, compromised guest VMs could potentially escape to the host.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Exploitation requires guest VM access and knowledge of the virglrenderer protocol. The vulnerability is in the VIRGL_CCMD_RESOURCE_INLINE_WRITE command handling.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: virglrenderer 0.8.1 and later

Vendor Advisory: https://access.redhat.com/security/cve/cve-2019-18389

Restart Required: Yes

Instructions:

1. Update virglrenderer to version 0.8.1 or later. 2. Update QEMU if using bundled virglrenderer. 3. Restart affected virtual machines. 4. Verify the fix by checking virglrenderer version.

🔧 Temporary Workarounds

Disable virglrenderer 3D acceleration

linux

Disable 3D acceleration using virglrenderer in QEMU/KVM virtual machine configurations

Edit VM configuration to remove or disable virglrenderer acceleration (e.g., remove '-device virtio-vga,virgl=on' or similar options)

🧯 If You Can't Patch

Isolate vulnerable VMs on separate hosts or networks to limit potential host compromise impact
Implement strict access controls to guest VMs and monitor for unusual activity

🔍 How to Verify

Check if Vulnerable:

Check virglrenderer version: 'virglrenderer --version' or check package version with 'rpm -q virglrenderer' or 'dpkg -l virglrenderer'

Check Version:

virglrenderer --version 2>/dev/null || rpm -q virglrenderer 2>/dev/null || dpkg -l virglrenderer 2>/dev/null | grep ^ii

Verify Fix Applied:

Verify virglrenderer version is 0.8.1 or later and check that the commit cbc8d8b75be360236cada63784046688aeb6d921 is included

📡 Detection & Monitoring

Log Indicators:

QEMU/VMM crash logs
Kernel oops or panic messages related to virglrenderer
Guest VM abnormal termination with virglrenderer errors

Network Indicators:

Unusual virglrenderer protocol traffic patterns from guest VMs

SIEM Query:

source="qemu.log" AND ("virglrenderer" OR "VIRGL_CCMD_RESOURCE_INLINE_WRITE") AND ("crash" OR "overflow" OR "panic")

📊 Metadata

CVE ID: CVE-2019-18389

CVSS v3 Score: 7.8 (HIGH)

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

CWE: CWE-787

Published: December 23, 2019

Last Updated: November 21, 2024

🔗 References

http://lists.opensuse.org/opensuse-security-announce/2020-01/msg00028.html Mailing List,Third Party Advisory
https://access.redhat.com/security/cve/cve-2019-18389 Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1765577 Issue Tracking,Patch,Third Party Advisory
https://gitlab.freedesktop.org/virgl/virglrenderer/commit/cbc8d8b75be360236cada63784046688aeb6d921 Patch,Third Party Advisory
https://gitlab.freedesktop.org/virgl/virglrenderer/merge_requests/314/diffs?commit_id=9c280a28651507e6ef87b17b90d47b6af3a4ab7d Patch,Third Party Advisory
https://lists.debian.org/debian-lts-announce/2022/12/msg00017.html Mailing List,Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-01/msg00028.html Mailing List,Third Party Advisory
https://access.redhat.com/security/cve/cve-2019-18389 Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1765577 Issue Tracking,Patch,Third Party Advisory
https://gitlab.freedesktop.org/virgl/virglrenderer/commit/cbc8d8b75be360236cada63784046688aeb6d921 Patch,Third Party Advisory
https://gitlab.freedesktop.org/virgl/virglrenderer/merge_requests/314/diffs?commit_id=9c280a28651507e6ef87b17b90d47b6af3a4ab7d Patch,Third Party Advisory
https://lists.debian.org/debian-lts-announce/2022/12/msg00017.html Mailing List,Third Party Advisory

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