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FirefoxWeb browser · Mozilla

CVE-2007-3827

MEDIUM · 5.0 CVSS v2.0 Published 2007-07-17
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
59/100
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
Mozilla Firefox allows for cookies to be set with a null domain (aka "domainless cookies"), which allows remote attackers to pass information between arbitrary domains and track user activity, as demonstrated by the domain attribute in the document.cookie variable in a javascript: window.

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

Mozilla Firefox versions allowed cookies to be set with a null or empty domain attribute via document.cookie, enabling remote attackers to set cookies that could be accessed across arbitrary domains and facilitating user activity tracking.

MitigationUpdate affected Firefox installations to patched versions; implement Content Security Policy headers to restrict cookie manipulation and consider browser endpoint management to ensure timely security updates.

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:all versions

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
Authentication
None
Confidentiality
Partial
Integrity
None
Availability
None

AV:N/AC:L/Au:N/C:P/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
    Navigate to about:support in the Firefox address bar or go to Help > About Firefox to view the version number
    Affected if The installed version is older than the patched release that addresses CVE-2007-3827 (Firefox 2.0.0.5 and later contain the fix)
  2. Confirm cookie domain handling behavior
    Open the JavaScript console (Ctrl+Shift+K), then execute: document.cookie = 'test=value; domain=; path=/'; Check if a cookie is set without a proper domain restriction
    Affected if A cookie is successfully set with an empty/null domain, indicating the vulnerability is present

If the Firefox version is older than the patched release or if cookies can be set with an empty domain attribute, the environment is affected by this CVE.

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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Update affected Firefox installations to patched versions; implement Content Security Policy headers to restrict cookie manipulation and consider browser endpoint management to ensure timely security updates.

Fix this in Firefox Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing1.0 h
  • Review / QA1.0 h
5.0 hours of engineering $910
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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-2007-3827 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