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FirefoxWeb browser · Mozilla

CVE-2014-8638

MEDIUM · 6.8 CVSS v2.0 Published 2015-01-14
Fix available
A fix is available. Upgrade to after 34.0.5 or later.
See remediation →
77/100
Remediation priority · High
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
The navigator.sendBeacon implementation in Mozilla Firefox before 35.0, Firefox ESR 31.x before 31.4, Thunderbird before 31.4, and SeaMonkey before 2.32 omits the CORS Origin header, which allows remote attackers to bypass intended CORS access-control checks and conduct cross-site request forgery (CSRF) attacks via a crafted web site.

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

The navigator.sendBeacon() API in affected Mozilla products fails to include the CORS Origin header in outgoing requests. This allows malicious websites to bypass origin checks and execute CSRF attacks against servers that rely on the Origin header for access control.

MitigationUpdate affected Mozilla products to Firefox 35.0+, Firefox ESR 31.4+, Thunderbird 31.4+, or SeaMonkey 2.32+ to receive the patch that ensures the Origin header is sent with beacon requests.

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:= 31.0= 31.1.0= 31.1.1= 31.3.0<= 34.0.5
Firefox EsrWeb browser
Affected:= 31.2
ThunderbirdApplication
Affected:<= 31.3.0
SeamonkeyApplication
Affected:<= 2.31

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
M
Authentication
None
Confidentiality
Partial
Integrity
Partial
Availability
Partial

AV:N/AC:M/Au:N/C:P/I:P/A:P

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 the installed Mozilla product
    Open the application and navigate to Help > About (Firefox/Thunderbird/SeaMonkey) or check the application name in the system
    Affected if The product is Firefox, Firefox ESR, Thunderbird, or SeaMonkey
  2. Check the product version number
    In Firefox: Go to Help > About Firefox. In Thunderbird: Go to Help > About Thunderbird. In SeaMonkey: Go to Help > About SeaMonkey. Record the exact version number shown (e.g., 31.0, 31.2, 34.0.5)
    Affected if The version cannot be determined or is not visible
  3. Compare Firefox version against affected range
    If using Firefox, verify if the version matches: 31.0, 31.1.0, 31.1.1, 31.3.0, or any version from 31.0 through 34.0.5 inclusive
    Affected if Version is 31.0, 31.1.0, 31.1.1, 31.3.0, or between 31.0 and 34.0.5 inclusive
  4. Compare Firefox ESR version against affected range
    If using Firefox ESR, verify if the version is 31.2
    Affected if Version is exactly 31.2
  5. Compare Thunderbird version against affected range
    If using Thunderbird, verify if the version is 31.3.0 or lower
    Affected if Version is 31.3.0 or lower
  6. Compare SeaMonkey version against affected range
    If using SeaMonkey, verify if the version is 2.31 or lower
    Affected if Version is 2.31 or lower

A user is affected if they are running any version of Firefox 31.0 through 34.0.5, Firefox ESR 31.2, Thunderbird 31.3.0 or lower, or SeaMonkey 2.31 or lower, and they use the sendBeacon() API in web content where CSRF protection relies on the Origin header.

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 34.0.5
Interim mitigation

Update affected Mozilla products to Firefox 35.0+, Firefox ESR 31.4+, Thunderbird 31.4+, or SeaMonkey 2.32+ to receive the patch that ensures the Origin header is sent with beacon requests.

Fix this in Firefox Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing2.0 h
  • Review / QA2.0 h
16.0 hours of engineering $2,900
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,640.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2014-8638 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

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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-2014-8638 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