LibvirtApplication · Redhat
CVE-2019-20485
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedqemu/qemu_driver.c in libvirt before 6.0.0 mishandles the holding of a monitor job during a query to a guest agent, which allows attackers to cause a denial of service (API blockage).
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · moderate confidenceIn libvirt's qemu/qemu_driver.c before version 6.0.0, the code improperly handles holding a monitor job when processing a query to a guest agent. This mismanagement can be exploited by attackers to cause a denial of service by blocking the libvirt API.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
LibvirtApplication
< 6.0.0
Debian LinuxOperating system
= 8.0= 9.0= 10.0
FedoraOperating system
= 31CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Adjacent
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
-
Check installed libvirt versionRun `rpm -qa | grep libvirt` (RHEL/Fedora) or `dpkg -l | grep libvirt` (Debian) to find the installed libvirt packages and their versions. Compare the version number to the affected range (versions before 6.0.0).Affected if The installed libvirt version is less than 6.0.0
-
Verify qemu driver is in useCheck if libvirt is configured to use the qemu driver. Look at /etc/libvirt/libvirtd.conf for lines containing `driver` or `qemu`. Alternatively, run `virsh connect` and check connection info.Affected if The qemu driver (qemu:///system or qemu:///session) is active
-
Confirm guest agent access is possibleCheck if the libvirt API for guest agent queries is accessible. Look for configurations in /etc/libvirt/qemu.conf or domain XML definitions that enable guest agent channels (`channel` type='virtio' with guestfwd or serial).Affected if Guest agent channels are configured and accessible to untrusted users
-
Look for denial of service symptomsCheck if libvirt API calls are hanging or blocked. Run `virsh list` or `virsh domstate <domain>` and observe if commands hang. Check system logs for any related errors.Affected if Libvirt API calls hang or timeout when querying domains with guest agents configured
A system is affected if it runs libvirt version less than 6.0.0 with the qemu driver enabled and has guest agent query access available, potentially showing blocked/hanging API calls.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor data6.0.0
Upgrade to libvirt 6.0.0 or later which contains the fix for the monitor job handling. If upgrade is not immediately possible, restrict access to guest agent query APIs to trusted users only.
Fix this in Libvirt
Scoped from the published advisory
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,800.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2019-20485 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2019-20485 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data