Mozilla

Mozilla Foundation Security Advisory 2012-51

X-Frame-Options header ignored when duplicated

Announced
July 17, 2012
Reporter
Frédéric Buclin
Impact
Moderate
Products
Firefox, Firefox ESR, SeaMonkey, Thunderbird, Thunderbird ESR
Fixed in
  • Firefox 14
  • Firefox ESR 10.0.6
  • SeaMonkey 2.11
  • Thunderbird 14
  • Thunderbird ESR 10.0.6

Description

Bugzilla developer Frédéric Buclin reported that the "X-Frame-Options header is ignored when the value is duplicated, for example X-Frame-Options: SAMEORIGIN, SAMEORIGIN. This duplication occurs for unknown reasons on some websites and when it occurs results in Mozilla browsers not being protected against possible clickjacking attacks on those pages

References