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FedoraOperating system · Fedoraproject

CVE-2016-7953

CRITICAL · 9.8 CVSS v3.0 Published 2016-12-13
Fix available
A fix is available. Upgrade to after 1.0.9 or later.
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
Buffer underflow in X.org libXvMC before 1.0.10 allows remote X servers to have unspecified impact via an empty string.

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 confidence

A buffer underflow vulnerability exists in X.org libXvMC (Video Motion Compensation library) versions prior to 1.0.10. The vulnerability is triggered when processing an empty string sent by a remote X server, causing the library to read or write before the beginning of a buffer. This can lead to memory corruption and potentially allow remote code execution with CRITICAL severity (CVSS 9.8).

MitigationUpgrade libXvMC to version 1.0.10 or later. Audit all systems running X11 servers or applications that link against libXvMC, as the vulnerable library may be loaded dynamically by X server components.

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
FedoraOperating system
Affected:= 24= 25
LibxvmcApplication
Affected:<= 1.0.9

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. Check if libXvMC library is installed
    On Linux, run 'rpm -qa | grep -i libxvmc' (RHEL/Fedora) or 'dpkg -l | grep -i libxvmc' (Debian/Ubuntu). On other systems, search for libXvMC.so files: 'find /usr -name "libXvMC*" 2>/dev/null'
    Affected if The library is present on the system
  2. Determine installed libXvMC version
    Run 'rpm -q libXvMC' (RHEL/Fedora) or 'dpkg -s libxvmc' (Debian/Ubuntu) to get the exact version number
    Affected if Version is lower than 1.0.10, or for Fedora systems if version matches 24 or 25 with libXvMC installed
  3. Check for X server components using libXvMC
    Search for executables that link against libXvMC: 'ldd /usr/bin/* 2>/dev/null | grep libXvMC' or check X11-related processes: 'ps aux | grep -E "Xorg|X11|X"'
    Affected if X server or X client applications are running that load libXvMC
  4. Verify if remote X connections are enabled
    Check X server configuration: 'grep -r "^xDMCP" /etc/X11/xdm/xdm-config' or 'grep -r "^Enable" /etc/gdm/custom.conf' or check listening ports: 'netstat -an | grep -E "600[0-9]|177"'
    Affected if The X server is configured to accept remote connections (xDMCP enabled or X listens on TCP port 6000+)

A system is affected if libXvMC version lower than 1.0.10 is installed AND the system runs an X server that can be reached remotely, allowing a malicious remote X server to send the triggering empty string.

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
Upgrade available Upgrade to a release after 1.0.9
Interim mitigation

Upgrade libXvMC to version 1.0.10 or later. Audit all systems running X11 servers or applications that link against libXvMC, as the vulnerable library may be loaded dynamically by X server components.

Recommended fix High confidence

libXvMC 1.0.10 or later (or Fedora package update containing the fix)

  1. Check current installed version: dnf list installed libxvmc
  2. Update package cache: dnf check-update
  3. Upgrade libxvmc to the fixed version: dnf update libxvmc
  4. Verify the new version is 1.0.10 or later: rpm -q libxvmc

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

Fix this in Fedora Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA2.0 h
20.0 hours of engineering $3,500
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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-2016-7953 in production — separate from our analysis above.

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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