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FirefoxWeb browser · Mozilla

CVE-2012-3956

HIGH · 10.0 CVSS v2.0 Published 2012-08-29
Fix available
A fix is available. Upgrade to 2.12 / 10.0.7 or later.
See remediation →
100/100
Remediation priority · Urgent
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
Use-after-free vulnerability in the MediaStreamGraphThreadRunnable::Run function in Mozilla Firefox before 15.0, Firefox ESR 10.x before 10.0.7, Thunderbird before 15.0, Thunderbird ESR 10.x before 10.0.7, and SeaMonkey before 2.12 allows remote attackers to execute arbitrary code or cause a denial of service (heap memory corruption) via unspecified vectors.

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

Use-after-free vulnerability in the MediaStreamGraphThreadRunnable::Run function allows remote attackers to execute arbitrary code or cause heap memory corruption. The vulnerability exists in Mozilla products handling media streams, specifically in Firefox before 15.0, Firefox ESR 10.x before 10.0.7, Thunderbird before 15.0, Thunderbird ESR 10.x before 10.0.7, and SeaMonkey before 2.12.

MitigationUpdate affected Mozilla products to the fixed versions: Firefox 15.0 or later, Firefox ESR 10.0.7 or later, Thunderbird 15.0 or later, Thunderbird ESR 10.0.7 or later, or SeaMonkey 2.12 or later.

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:< 15.0>= 10.0, < 10.0.7
Enterprise Linux DesktopOperating system
Affected:= 5.0= 6.0
Enterprise Linux EusOperating system
Affected:= 6.3
Enterprise Linux ServerOperating system
Affected:= 5.0= 6.0
Enterprise Linux Server EusOperating system
Affected:= 6.3
Enterprise Linux WorkstationOperating system
Affected:= 5.0= 6.0
Ubuntu LinuxOperating system
Affected:= 10.04= 11.04= 11.10= 12.04
SeamonkeyApplication
Affected:< 2.12

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
Complete
Integrity
Complete
Availability
Complete

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

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
    In Firefox, go to Help > About Firefox, or run: firefox --version
    Affected if Version is below 15.0, or is 10.x but below 10.0.7 (ESR)
  2. Check Thunderbird version
    In Thunderbird, go to Help > About Thunderbird, or run: thunderbird --version
    Affected if Version is below 15.0, or is 10.x but below 10.0.7 (ESR)
  3. Check SeaMonkey version
    In SeaMonkey, go to Help > About SeaMonkey, or run: seamonkey --version
    Affected if Version is below 2.12
  4. Check packaged Mozilla product versions on Red Hat/Ubuntu
    On RHEL/CentOS: rpm -qa | grep -E 'firefox|thunderbird|seamonkey'. On Ubuntu: dpkg -l | grep -E 'firefox|thunderbird|seamonkey'
    Affected if Installed package version matches the vulnerable Red Hat or Ubuntu versions listed (Firefox/Thunderbird 10.x before 10.0.7 on Ubuntu 10.04-12.04, or Firefox on RHEL 5/6)
  5. Identify if media streaming features are in use
    The vulnerability is in the MediaStreamGraphThreadRunnable media handling code. Check if the browser has been used for WebRTC, audio/video playback, or HTML5 media features. These features are built-in and cannot be disabled to mitigate.
    Affected if The affected version is running and media features have been accessed (any use of audio/video in the browser triggers the vulnerable code path)

A user is affected if they run Firefox < 15.0 or Firefox ESR 10.x < 10.0.7, Thunderbird < 15.0 or Thunderbird ESR 10.x < 10.0.7, or SeaMonkey < 2.12.

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.

dbcve · scoped
Upgrade available Upgrade to 2.12 / 10.0.7 / 15.0 or later
Fixed in 2.1210.0.715.0
Interim mitigation

Update affected Mozilla products to the fixed versions: Firefox 15.0 or later, Firefox ESR 10.0.7 or later, Thunderbird 15.0 or later, Thunderbird ESR 10.0.7 or later, or SeaMonkey 2.12 or later.

Recommended fix High confidence

Firefox 15.0 or Firefox ESR 10.0.7; Thunderbird 15.0 or Thunderbird ESR 10.0.7; SeaMonkey 2.12

  1. For Firefox users: Upgrade to Firefox 15.0 or later. For Firefox ESR 10.x users: Upgrade to Firefox ESR 10.0.7 or later.
  2. For Thunderbird users: Upgrade to Thunderbird 15.0 or later. For Thunderbird ESR 10.x users: Upgrade to Thunderbird ESR 10.0.7 or later.
  3. For SeaMonkey users: Upgrade to SeaMonkey 2.12 or later.
  4. On Red Hat Enterprise Linux / CentOS systems: Run 'yum update firefox' or 'yum update thunderbird' to apply the security patches.
  5. On Ubuntu/Debian systems: Run 'apt-get update && apt-get upgrade firefox' or 'apt-get update && apt-get upgrade thunderbird' to get the patched versions.
Caveat Upgrading to a new major version (e.g., Firefox 15.0) may introduce changes to extensions or preferences; ESR versions are recommended for organizations requiring stability.

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Firefox Scoped from the published advisory
  • Consultation2.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA3.0 h
19.0 hours of engineering $3,280
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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-2012-3956 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