LibvirtApplication · Redhat
CVE-2017-1000256
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 · uneditedlibvirt version 2.3.0 and later is vulnerable to a bad default configuration of "verify-peer=no" passed to QEMU by libvirt resulting in a failure to validate SSL/TLS certificates by default.
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 confidencelibvirt versions 2.3.0 and later pass a default configuration of 'verify-peer=no' to QEMU, disabling SSL/TLS certificate validation. This allows man-in-the-middle attackers to intercept and modify encrypted communications between libvirt and QEMU by presenting fraudulent certificates.
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
>= 2.3.0, < 3.9.0
Debian LinuxOperating system
= 9.0CVSS 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
- Network
- Complexity
- High
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/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.
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Identify installed libvirt versionRun 'rpm -qa | grep libvirt' (RHEL) or 'dpkg -l | grep libvirt' (Debian) to list installed libvirt packages, or use 'libvirtd --version' to get the daemon versionAffected if The installed version falls within >= 2.3.0 and < 3.9.0 (Red Hat) or equals 9.0 (Debian)
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Locate libvirt QEMU configuration fileThe default configuration is typically located at /etc/libvirt/qemu.conf or in /etc/libvirt/libvirtd.conf. Search for files containing 'verify-peer' settingAffected if The configuration file exists and contains 'verify-peer=no' or lacks a 'verify-peer' setting entirely (defaults to no)
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Inspect TLS certificate configuration for QEMUCheck if 'listen_tls' is set to 1 in the libvirt configuration, and examine the 'key_file', 'cert_file', and 'ca_file' settings that define TLS credentialsAffected if TLS is enabled (listen_tls=1) but verify-peer is disabled or unset, creating the vulnerable condition
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Check for custom connection URIsReview any libvirt client connection configurations or scripts that may override default settings. Look for 'qemu+tls://' versus 'qemu://' URI schemes in useAffected if Connections to QEMU use TLS transport but certificate verification is not explicitly enforced
A system is affected if it runs a vulnerable libvirt version (2.3.0 to 3.9.0 on RHEL, or 9.0 on Debian) AND has TLS-enabled QEMU connections with verify-peer disabled or not explicitly set to 'yes'.
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 data3.9.0
Reconfigure libvirt to enable peer certificate verification ('verify-peer=yes' or equivalent) and ensure proper TLS certificate validation is enforced for all QEMU connections.
Fix this in Libvirt
Scoped from the published advisory
- Consultation2.0 h
- Implementation1.0 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 $1,936.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2017-1000256 — 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-2017-1000256 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
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- Version or environment caveats, and links to real fixes
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