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FirefoxWeb browser · Mozilla

CVE-2018-5114

MEDIUM · 5.3 CVSS v3.0 Published 2018-06-11
Fix available
A fix is available. Upgrade to after 57.0.4 or later.
See remediation →
62/100
Remediation priority · Elevated
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
If an existing cookie is changed to be "HttpOnly" while a document is open, the original value remains accessible through script until that document is closed. Network requests correctly use the changed HttpOnly cookie. This vulnerability affects 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

When an existing cookie is modified to add the HttpOnly flag while a document remains open, JavaScript can continue to access the original cookie value until the document closes, even though network requests correctly use the HttpOnly-protected cookie. This creates an information disclosure window where script can read cookie values that should be protected from script access.

MitigationUpgrade Firefox to version 58 or later to resolve this vulnerability.

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
FirefoxWeb browser
Affected:<= 57.0.4
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
Low
Integrity
None
Availability
None

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

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 installed Firefox version
    Open Firefox, click the menu button, go to Help > About Firefox. Alternatively, run 'firefox --version' from command line.
    Affected if Version displayed is 57.0.4 or lower (any version up to and including 57.0.4)
  2. Confirm version matches CVE range
    Compare the installed version number to the affected range. Firefox versions 58.0 and later are NOT vulnerable.
    Affected if Installed version is 57.0.4 or earlier, or any version beginning with 57.0.x where x is 0-4

You are affected if Firefox version 57.0.4 or earlier is installed; versions 58.0 and later are not vulnerable to this issue.

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.

From vendor data
Upgrade available Upgrade to a release after 57.0.4
Interim mitigation

Upgrade Firefox to version 58 or later to resolve this vulnerability.

Fix this in Firefox Scoped from the published advisory
  • Consultation1.0 h
  • Implementation1.0 h
  • Testing0.5 h
  • Review / QA0.5 h
3.0 hours of engineering $750
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,200.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

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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-2018-5114 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