dbcve.org
Enterprise Linux DesktopOperating system · Redhat

CVE-2018-5156

CRITICAL · 9.8 CVSS v3.0 Published 2018-10-18
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
A vulnerability can occur when capturing a media stream when the media source type is changed as the capture is occurring. This can result in stream data being cast to the wrong type causing a potentially exploitable crash. This vulnerability affects Thunderbird < 60, Firefox ESR < 60.1, Firefox ESR < 52.9, and Firefox < 61.

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

Type confusion vulnerability in Firefox/Thunderbird media capture where stream data is cast to the wrong type when the media source type changes during active capture, leading to a potentially exploitable crash.

MitigationUpgrade to Firefox 61+, Firefox ESR 60.1+/52.9+, or Thunderbird 60+ to remediate. If immediate patching is not possible, disable media capture functionality as a compensating control.

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
Enterprise Linux DesktopOperating system
Affected:= 6.0= 7.0
Enterprise Linux ServerOperating system
Affected:= 6.0= 7.0
Enterprise Linux Server AusOperating system
Affected:= 7.6
Enterprise Linux Server EusOperating system
Affected:= 7.5= 7.6
Enterprise Linux Server TusOperating system
Affected:= 7.6
Enterprise Linux WorkstationOperating system
Affected:= 6.0= 7.0
Debian LinuxOperating system
Affected:= 8.0= 9.0
Ubuntu LinuxOperating system
Affected:= 14.04= 16.04= 17.10= 18.04

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 if Firefox is installed
    Run 'firefox --version' or check package manager: 'rpm -qa | grep firefox' (RHEL) or 'dpkg -l | grep firefox' (Debian/Ubuntu)
    Affected if Firefox version is below 61.0, or ESR version is below 60.1 (or 52.9 for older ESR), meaning the installed package ships a vulnerable browser binary
  2. Identify if Thunderbird is installed
    Run 'thunderbird --version' or check package manager: 'rpm -qa | grep thunderbird' (RHEL) or 'dpkg -l | grep thunderbird' (Debian/Ubuntu)
    Affected if Thunderbird version is below 60.0, meaning the installed package ships a vulnerable email client with media capture capabilities
  3. Check OS version as secondary context
    Run 'cat /etc/os-release' or 'hostnamectl' to confirm the distribution version
    Affected if Running RHEL 6.0/7.0, Debian 8.0/9.0, Ubuntu 14.04/16.04/17.10/18.04, or RHEL Server Aus/Eus/Tus 7.5/7.6 - these shipped vulnerable Firefox/Thunderbird versions by default
  4. Verify media capture functionality is accessible
    Check if the browser can access media devices via 'about:support' in Firefox or Thunderbird, or look for permission prompts for camera/microphone access
    Affected if Media capture permissions are granted or available - the vulnerability triggers when actively capturing media and the source type changes mid-stream

A user is affected if they run Firefox below 61.0 (or ESR below 60.1/52.9) or Thunderbird below 60.0 on the listed OS versions, AND have media capture functionality accessible in their environment.

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

Upgrade to Firefox 61+, Firefox ESR 60.1+/52.9+, or Thunderbird 60+ to remediate. If immediate patching is not possible, disable media capture functionality as a compensating control.

Recommended fix High confidence

Firefox >= 61, Firefox ESR >= 60.1 or >= 52.9, Thunderbird >= 60

  1. Update the package repository metadata: 'sudo yum check-update' (RHEL/CentOS) or 'sudo apt-get update' (Debian/Ubuntu)
  2. Upgrade Firefox to version 61 or higher (or Firefox ESR 60.1+/52.9+) using: 'sudo yum update firefox' or 'sudo apt-get install firefox'
  3. Upgrade Thunderbird to version 60 or higher using: 'sudo yum update thunderbird' or 'sudo apt-get install thunderbird'
  4. Restart any running Firefox or Thunderbird instances
  5. Verify the installed version: 'firefox --version' or 'thunderbird --version'
Caveat Major version upgrades (e.g., Firefox 52 to 60) may change add-on compatibility and user preferences

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

Fix this in Enterprise Linux Desktop Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing2.0 h
  • Review / QA1.0 h
9.0 hours of engineering $1,600
Get help mitigating

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,560.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2018-5156 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

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-2018-5156 in production — separate from our analysis above.

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.

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