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FirefoxWeb browser · Mozilla

CVE-2015-0807

MEDIUM · 6.8 CVSS v2.0 Published 2015-04-01
Fix available
A fix is available. Upgrade to after 36.0.4 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 37.0, Firefox ESR 31.x before 31.6, and Thunderbird before 31.6 processes HTTP 30x status codes for redirects after a preflight request has occurred, which allows remote attackers to bypass intended CORS access-control checks and conduct cross-site request forgery (CSRF) attacks via a crafted web site, a similar issue to CVE-2014-8638.

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 Firefox before 37.0 and Thunderbird before 31.6 improperly processes HTTP 30x redirects that occur after a CORS preflight request, allowing attackers to bypass cross-origin access controls and conduct CSRF attacks against web applications using this API.

MitigationUpdate affected Mozilla products to patched versions (Firefox 37.0+, Firefox ESR 31.6+, Thunderbird 31.6+) to remediate 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:<= 36.0.4= 31.0= 31.1.0= 31.1.1= 31.3.0= 31.5.1= 31.5.2= 31.5.3
Firefox EsrWeb browser
Affected:= 31.1= 31.2= 31.3= 31.4= 31.5
ThunderbirdApplication
Affected:<= 31.5

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. Check Firefox version
    Open Firefox, click the menu button, select Help, then About Firefox. Note the version number displayed.
    Affected if The installed version is 36.0.4 or earlier, or exactly 31.0, 31.1.0, 31.1.1, 31.3.0, 31.5.1, 31.5.2, or 31.5.3
  2. Check Firefox ESR version
    Open Firefox ESR, click the menu button, select Help, then About Firefox. Note the version number displayed.
    Affected if The installed version is exactly 31.1, 31.2, 31.3, 31.4, or 31.5
  3. Check Thunderbird version
    Open Thunderbird, click the menu button, select Help, then About Thunderbird. Note the version number displayed.
    Affected if The installed version is 31.5 or earlier

If the installed Firefox version is 36.0.4 or below or any of the specific 31.x versions listed, or Firefox ESR is 31.1 through 31.5, or Thunderbird is 31.5 or below, the browser is vulnerable to CORS bypass via sendBeacon redirects.

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 36.0.4
Interim mitigation

Update affected Mozilla products to patched versions (Firefox 37.0+, Firefox ESR 31.6+, Thunderbird 31.6+) to remediate this vulnerability.

Fix this in Firefox Scoped from the published advisory
  • Consultation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
4.0 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

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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-2015-0807 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