Mozilla Foundation Security Advisory 2011-34

Protection against fraudulent DigiNotar certificates

August 30, 2011
Firefox, Firefox Mobile, SeaMonkey, Thunderbird
Fixed in
  • Firefox 3.6.21
  • Firefox 6.0.1
  • Firefox Mobile 6.0.1
  • SeaMonkey 2.3.2
  • Thunderbird 3.1.13
  • Thunderbird 6.0.1

Description: Google Chrome user alibo encountered an active "man in the middle" (MITM) attack on secure SSL connections to Google servers. The fraudulent certificate was mis-issued by DigiNotar, a Dutch Certificate Authority. DigiNotar has reported evidence that other fraudulent certificates were issued and in active use but the full extent of the compromise is not known.

For the protection of our users Mozilla has removed the DigiNotar root certificate. Sites using certificates issued by DigiNotar will need to seek another certificate vendor.

Mozilla thanks Google, Inc. for reporting this issue to us. We also thank Marien Zwart (Mozilla Localization), Ot van Daalen (Bits of Freedom), and Erik de Jong (GovCERT) for their help.