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Debian LinuxOperating system · Debian

CVE-2018-5096

CRITICAL · 9.8 CVSS v3.0 Published 2018-06-11
Fix available
A fix is available. Upgrade to 52.6.0 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 while editing events in form elements on a page, resulting in a potentially exploitable crash. This vulnerability affects Firefox ESR < 52.6 and Thunderbird < 52.6.

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 use-after-free vulnerability exists in Firefox ESR and Thunderbird versions prior to 52.6, occurring in the event handling code for form elements. When editing events in form elements, memory is accessed after being freed, potentially allowing arbitrary code execution.

MitigationUpgrade to Firefox ESR 52.6 or later, and Thunderbird 52.6 or later, to patch the use-after-free vulnerability in form element event handling.

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 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 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:< 52.6.0

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 Firefox is installed
    Run 'firefox --version' or check the package manager (dpkg -l firefox or rpm -qi firefox)
    Affected if Firefox version is found to be less than 52.6.0
  2. Check if Thunderbird is installed
    Run 'thunderbird --version' or check the package manager (dpkg -l thunderbird or rpm -qi thunderbird)
    Affected if Thunderbird version is found and is less than 52.6.0
  3. Verify installed version against affected range
    Compare the discovered Firefox version number to the affected range: versions prior to 52.6.0
    Affected if The installed Firefox version is below 52.6.0 (for example, 52.5.0, 52.0, or earlier)
  4. Confirm the vulnerable component is present
    The vulnerability affects form element event handling, which is a built-in feature of Firefox and Thunderbird browsers and cannot be disabled
    Affected if The browser is running and can process HTML forms (the vulnerable code path is always present in affected versions)

A user is affected if they have Firefox installed with a version lower than 52.6.0, as the use-after-free flaw in form element event handling is present in all such versions.

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 or later
Fixed in 52.6.0
Interim mitigation

Upgrade to Firefox ESR 52.6 or later, and Thunderbird 52.6 or later, to patch the use-after-free vulnerability in form element event handling.

Recommended fix High confidence

Firefox ESR 52.6 or later / Thunderbird 52.6 or later; or Debian/RHEL security updates containing the Firefox/Thunderbird 52.6 patch

  1. Check installed Firefox or Thunderbird version: 'firefox --version' or 'thunderbird --version'
  2. For Debian systems: Run 'apt-get update && apt-get upgrade' to apply security updates
  3. For RHEL/CentOS systems: Run 'yum update' to apply security updates
  4. Restart the browser/application after updating
  5. Verify the version is now 52.6.0 or higher
Caveat This is a security-only update; Firefox 52.x ESR is a stable release with no expected breaking changes for typical users

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

Fix this in Debian Linux Scoped from the published advisory
  • Consultation1.0 h
  • Implementation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
5.0 hours of engineering $860
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,376.

Scan for this in your stack

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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-2018-5096 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