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Debian LinuxOperating system · Debian

CVE-2016-0749

CRITICAL · 9.8 CVSS v3.0 Published 2016-06-09
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

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 · unedited
The smartcard interaction in SPICE allows remote attackers to cause a denial of service (QEMU-KVM process crash) or possibly execute arbitrary code via vectors related to connecting to a guest VM, which triggers a heap-based buffer overflow.

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 · high confidence

Heap-based buffer overflow in the SPICE protocol's smartcard interaction component. When a remote attacker connects to a guest VM, the smartcard handling code fails to properly validate buffer sizes during the connection process, leading to heap memory corruption that can crash the QEMU-KVM process or potentially allow arbitrary code execution.

MitigationApply the QEMU-KVM security patch for CVE-2016-0749 to all affected virtualization hosts. As a compensating control, disable the smartcard redirection feature in SPICE if not required, or restrict SPICE network access to trusted clients only.

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
Debian LinuxOperating system
Affected:= 8.0
Enterprise LinuxOperating system
Affected:= 6.0= 7.0
Enterprise Linux DesktopOperating system
Affected:= 6.0= 7.0
Enterprise Linux ServerOperating system
Affected:= 6.0= 7.0
Enterprise Linux WorkstationOperating system
Affected:= 6.0= 7.0
Enterprise Linux Hpc Node EusOperating system
Affected:= 7.2
Enterprise Linux Server AusOperating system
Affected:= 7.2
Enterprise Linux Server EusOperating system
Affected:= 7.2

CVSS 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
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.0/AV:N/AC:L/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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify QEMU-KVM version
    Run 'rpm -q qemu-kvm' on RHEL or 'dpkg -l qemu-kvm' on Debian to get the installed version, then compare against affected version ranges (RHEL 6.0, 7.0, 7.2; Debian 8.0)
    Affected if The installed version matches an affected version listed in the CVE advisory
  2. Confirm SPICE display protocol is in use
    Check VM configuration XML (virsh dumpxml <vmname>) or VM settings for '<graphics type="spice">' or check running processes for 'qemu-kvm.*-spice'
    Affected if SPICE graphics are configured for the VM
  3. Verify smartcard redirection is enabled
    Look for '<redirdev>' or '<smartcard>' elements in VM XML configuration (virsh dumpxml <vmname>), or check for '-device usb-redir,smartcard' in qemu command line (ps aux | grep qemu)
    Affected if Smartcard redirection device is attached to the VM (type='smartcard' or similar)
  4. Assess network exposure of SPICE port
    Check VM XML for '<listen type="address">' under graphics or run 'netstat -tlnp | grep -i spice' to see if SPICE listens on 0.0.0.0 or non-loopback interface
    Affected if SPICE port (typically 5900+) is bound to a network interface accessible to untrusted clients

You are affected if running an affected QEMU-KVM version with SPICE smartcard redirection enabled and the SPICE interface is exposed to untrusted network access.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the QEMU-KVM security patch for CVE-2016-0749 to all affected virtualization hosts. As a compensating control, disable the smartcard redirection feature in SPICE if not required, or restrict SPICE network access to trusted clients only.

Recommended fix High confidence

Upgrade to the latest available package versions in the distribution's security repositories that address CVE-2016-0749. For RHEL, this is available via RHSA-2016:0043 or subsequent errata. For Debian 8 (Jessie), this is available in security updates.

  1. 1. Identify the affected SPICE and QEMU-KVM packages installed on the system using the package manager (e.g., yum, rpm, apt).
  2. 2. For Debian systems: Run 'apt-get update' followed by 'apt-get upgrade' or 'apt-get install --only-upgrade <package-name>' to apply security updates.
  3. 3. For RHEL/CentOS systems: Run 'yum update' or 'yum update qemu-kvm spice-server' to apply the latest security patches.
  4. 4. After updating, restart the QEMU-KVM virtual machines or the libvirt service to ensure the patched libraries are loaded.
  5. 5. Verify the installed versions are no longer vulnerable by checking the package version against the security advisory.
Caveat Standard upgrade risk: test in non-production environment first as QEMU-KVM updates may require VM restart and could affect running workloads.

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Debian Linux Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing3.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,490
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2016-0749 in production — separate from our analysis above.

No notes yet

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What this is

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.

What belongs here
  • 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