dbcve.org
Debian LinuxOperating system · Debian

CVE-2018-5103

CRITICAL · 9.8 CVSS v3.0 Published 2018-06-11
Fix available
A fix is available. Upgrade to 52.6.0 / 58.0 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
A use-after-free vulnerability can occur during mouse event handling due to issues with multiprocess support. This results in a potentially exploitable crash. This vulnerability affects Thunderbird < 52.6, Firefox ESR < 52.6, and Firefox < 58.

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

A use-after-free vulnerability exists in the mouse event handling code of Firefox, Firefox ESR, and Thunderbird due to issues with multiprocess support. This memory safety flaw allows an attacker to potentially exploit a crash by freeing memory while it's still being referenced, leading to arbitrary code execution.

MitigationApply vendor patches by updating to Firefox 58 or later, Firefox ESR 52.6 or later, or Thunderbird 52.6 or later.

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:= 7.0= 8.0= 9.0
Enterprise Linux DesktopOperating system
Affected:= 6.0= 7.0
Enterprise Linux ServerOperating system
Affected:= 6.0= 7.0
Enterprise Linux Server AusOperating system
Affected:= 7.4
Enterprise Linux Server EusOperating system
Affected:= 7.4= 7.5
Enterprise Linux WorkstationOperating system
Affected:= 6.0= 7.0
FirefoxWeb browser
Affected:< 58.0< 52.6.0
Ubuntu LinuxOperating system
Affected:= 14.04= 16.04= 17.10

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 installed Mozilla product
    Check which application is installed: Firefox, Firefox ESR, or Thunderbird. On Linux, run `dpkg -l | grep -E 'firefox|thunderbird'` or `rpm -qa | grep -E 'firefox|thunderbird'`. On Windows, check Program Files for the application folder.
    Affected if Any of these products are installed (Firefox, Firefox ESR, or Thunderbird)
  2. Determine installed version
    For Firefox/Thunderbird: Run `firefox --version` or `thunderbird --version`. Alternatively, check the package manager output from step 1 for the exact version number.
    Affected if Firefox version is below 58.0 OR Firefox ESR/Thunderbird version is below 52.6.0
  3. Verify multiprocess support is enabled
    In Firefox/Thunderbird, navigate to about:support and look for 'Multiprocess Windows' or 'e10s' status. Alternatively, check for presence of the e10s preference in about:config (preference 'browser.tabs.remote.autostart' or similar).
    Affected if Multiprocess support (e10s) is enabled - this is required for the vulnerability to be exploitable
  4. Check OS distribution version
    On Linux, run `cat /etc/os-release` or `lsb_release -a` to identify the OS version.
    Affected if Running Debian 7.0, 8.0, or 9.0; Ubuntu 14.04, 16.04, or 17.10; or RHEL 6.0, 7.0, 7.4, or 7.5 with an affected Mozilla product version

User is affected if they have Firefox below 58.0 or Firefox ESR/Thunderbird below 52.6.0 installed AND have multiprocess (e10s) support enabled, regardless of underlying OS distribution.

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 52.6.0 / 58.0 or later
Fixed in 52.6.058.0
Interim mitigation

Apply vendor patches by updating to Firefox 58 or later, Firefox ESR 52.6 or later, or Thunderbird 52.6 or later.

Recommended fix High confidence

Firefox 58.0+, Firefox ESR 52.6.0+, or Thunderbird 52.6+

  1. 1. Identify which Mozilla product is affected (Firefox, Firefox ESR, or Thunderbird)
  2. 2. Close all instances of the affected application
  3. 3. For Firefox: Upgrade to version 58.0 or later
  4. 4. For Firefox ESR: Upgrade to version 52.6.0 or later
  5. 5. For Thunderbird: Upgrade to version 52.6 or later
  6. 6. On Linux systems (Debian/Ubuntu/Red Hat), use the system package manager: apt-get update && apt-get upgrade (Debian/Ubuntu) or yum update (RHEL)
  7. 7. Restart the application after upgrade
  8. 8. Verify the installed version matches or exceeds the fixed release
Caveat Firefox 58 introduced WebExtension API changes and removed legacy add-on support; some older extensions may be incompatible

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

Fix this in Debian Linux 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 the upgrade done

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-2018-5103 — 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-2018-5103 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