Mozilla Foundation Security Advisory 2014-73

RSA Signature Forgery in NSS

September 24, 2014
Antoine Delignat-Lavaud
Firefox, Firefox ESR, Firefox OS, NSS, SeaMonkey, Thunderbird
Fixed in
  • Firefox 32.0.3
  • Firefox ESR 24.8.1
  • Firefox ESR 31.1.1
  • Firefox OS 2.2
  • NSS
  • NSS 3.16.5
  • NSS 3.17.1
  • SeaMonkey 2.29.1
  • Thunderbird 24.8.1
  • Thunderbird 31.1.2


Antoine Delignat-Lavaud, security researcher at Inria Paris in team Prosecco, reported an issue in Network Security Services (NSS) libraries affecting all versions. He discovered that NSS is vulnerable to a variant of a signature forgery attack previously published by Daniel Bleichenbacher. This is due to lenient parsing of ASN.1 values involved in a signature and could lead to the forging of RSA certificates.

The Advanced Threat Research team at Intel Security also independently discovered and reported this issue.

These have been addressed in the NSS releases shipping on affected Mozilla products:

  • Firefox ESR 31.1.1, Firefox ESR 24.8.1, Thunderbird 31.1.1, and Thunderbird 24.8.1 have been updated to NSS
  • Firefox 32.0.3 and SeaMonkey 2.29.1 have been updated to 3.16.5.

Projects using NSS 3.17 should update the new 3.17.1 release.