FirefoxWeb browser · Mozilla

CVE-2015-7210

HIGH · 7.5 CVSS v2.0 Published 2015-12-16

Fix available

A fix is available. Upgrade to after 42.0 or later.

See remediation →

84/100

Remediation priority · High

Remotely reachable No privileges Zero-click

Official description

NVD · unedited

Use-after-free vulnerability in Mozilla Firefox before 43.0 and Firefox ESR 38.x before 38.5 allows remote attackers to execute arbitrary code by triggering attempted use of a data channel that has been closed by a WebRTC function.

Technical summary

dbcve analysis · high confidence

A use-after-free vulnerability exists in Mozilla Firefox before version 43.0 and Firefox ESR 38.x before 38.5. The flaw occurs when a WebRTC function attempts to use a data channel that has already been closed, causing the browser to reference freed memory and potentially allowing remote attackers to execute arbitrary code.

MitigationUpgrade Firefox to version 43.0 or later, or Firefox ESR to version 38.5 or later, to eliminate the use-after-free condition in the WebRTC data channel handling code.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions

NVD · CPE data

FirefoxWeb browser

Affected:<= 42.0= 38.0= 38.0.1= 38.0.5= 38.1.0= 38.1.1= 38.2.0= 38.2.1= 38.3.0= 38.4.0

FedoraOperating system

Affected:= 22= 23

LeapOperating system

Affected:= 42.1

OpensuseOperating system

Affected:= 13.1= 13.2

CVSS breakdown

From the vector

Attack vector: Network
Complexity: Low
Authentication: None
Confidentiality: Partial
Integrity: Partial
Availability: Partial

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

Am I affected?

dbcve checks

Work through these to decide whether this CVE applies to you.

Identify Firefox version

Open Firefox, click Help > About Firefox, or visit about:support, or run 'firefox --version' from command line. Note the full version number (e.g., 42.0, 38.5, 38.4.0).

Affected if Version is 42.0 or lower, or ESR 38.0 through 38.4.x (any version before 38.5). Version 43.0 and later, or ESR 38.5 and later, are NOT affected.
Confirm WebRTC is enabled

In Firefox address bar, type 'about:config' and press Enter. Search for 'media.peerconnection.enabled'. Check if the value is set to 'true'.

Affected if WebRTC is enabled (media.peerconnection.enabled = true). The vulnerability only triggers when WebRTC data channels are in use.
Check if WebRTC data channels are in use

Look for any active WebRTC sessions in the browser. This can include: active calls in web-based communication apps, any website using RTCPeerConnection, or browser extensions using WebRTC. Also check if any about:webrtc page shows active connections.

Affected if WebRTC data channels exist and may be closed while still being referenced by the application code. The use-after-free occurs when a closed data channel is accessed.

You are affected if your Firefox version is below 43.0 (or ESR below 38.5) AND WebRTC (media.peerconnection.enabled) is enabled and being used, allowing a closed data channel to trigger the use-after-free condition.

Generated from the published advisory. Verify against your own configuration.

Remediation

From vendor data

Upgrade available Upgrade to a release after 42.0

Interim mitigation

Upgrade Firefox to version 43.0 or later, or Firefox ESR to version 38.5 or later, to eliminate the use-after-free condition in the WebRTC data channel handling code.

Fix this in Firefox Scoped from the published advisory

Consultation2.0 h
Implementation4.0 h
Testing3.0 h
Review / QA1.0 h

10.0 hours of engineering $1,750

Get the upgrade done

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Scan for this in your stack

Free · runs locally

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References

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2015-7210 in production — separate from our analysis above.

Notes0 Guidelines

Know something about CVE-2015-7210?

The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.

The version that genuinely resolved it — not the one the vendor claimed
A config change or rule that shut the vector down
A gotcha in the upgrade path that cost you an afternoon

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

At a glance

A fix existsUpgrade to after 42.0 or later

Severity 7.5 High

Exploit likelihood EPSS, next 30 days 4.3%

Affects: Firefox

Remediation

A high-priority fix

Fix this in Firefox 10 hrs · Moderate

Typical engagement from $1,750

Get a fix See the full breakdown ↓

A high-priority vulnerability. Send your environment and a specialist will scope CVE-2015-7210 and return a fixed quote and timeline.

You’ll deal with our team directly and deploy the reviewed fix to staging first — never straight to production.

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.

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.

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.

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.

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.

Check your environment

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.

Scan for this in your stack

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Practitioner notes

No notes yet

Official description

Technical summary

Affected products & versions

CVSS breakdown

Am I affected?

Remediation

References