VU#791496: Mozilla Firefox SVG animation nsSMILTimeContainer use-after-free vulnerability

Vulnerability Note VU#791496

Mozilla Firefox SVG animation nsSMILTimeContainer use-after-free vulnerability

Original Release date: 30 Nov 2016 | Last revised: 02 Dec 2016


Mozilla Firefox contains a use-after-free vulnerability in the SVG animation functionality, which may allow a remote, unauthenticated attacker to execute arbitrary code on a vulnerable system.


Mozilla Firefox supports SVG animation through the use of SMIL. The nsSMILTimeContainer object contains a use-after-free vulnerability, which can allow arbitrary code execution.

Exploit code for this vulnerability is publicly available, which specifically targets the Tor Browser Bundle.


By convincing a use to view specially-crafted web content, a remote-unauthenticated attacker may be able to execute arbitrary code on an affected system.


Apply an update

This issue is addressed in Tor Browser 6.0.7 and Mozilla Firefox versions 50.0.2 and 45.5.1 ESR, as well as Thunderbird 45.5.1.

Disable JavaScript

This vulnerability can be mitigated by disabling JavaScript. This can be accomplished through use of the NoScript Firefox add-on.

Use the Microsoft Enhanced Mitigation Experience Toolkit

The Microsoft Enhanced Mitigation Experience Toolkit (EMET) can be used to help prevent exploitation of this and other vulnerabilities. Limited testing has shown that the following mitigations present in EMET 4.0 and later blog the public exploit for this vulnerability:

  • StackPivot
  • EAF
  • Caller

Vendor Information (Learn More)

Vendor Status Date Notified Date Updated
Mozilla Affected 30 Nov 2016
Tor Affected 30 Nov 2016

If you are a vendor and your product is affected, let
us know

CVSS Metrics (Learn More)

Group Score Vector
Base 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P
Temporal 6.5 E:H/RL:OF/RC:C
Environmental 6.5 CDP:ND/TD:H/CR:ND/IR:ND/AR:ND



This document was written by Will Dormann.

Other Information

  • CVE IDs:
  • Date Public:
    29 Nov 2016
  • Date First Published:
    30 Nov 2016
  • Date Last Updated:
    02 Dec 2016
  • Document Revision:


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