By rewriting the Host: request headers using the webRequest API, a WebExtension can bypass domain restrictions through domain fronting. This would allow access to domains that share a host that are otherwise restricted. This vulnerability affects Firefox ESR < 60.3 and Firefox < 63.
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{ "availability": "No subscription required", "binaries": [ { "binary_version": "63.0+build2-0ubuntu0.16.04.2", "binary_name": "firefox" }, { "binary_version": "63.0+build2-0ubuntu0.16.04.2", "binary_name": "firefox-dev" }, { "binary_version": "63.0+build2-0ubuntu0.16.04.2", "binary_name": "firefox-globalmenu" }, { "binary_version": "63.0+build2-0ubuntu0.16.04.2", "binary_name": "firefox-mozsymbols" }, { "binary_version": "63.0+build2-0ubuntu0.16.04.2", "binary_name": "firefox-testsuite" } ] }
{ "availability": "No subscription required", "binaries": [ { "binary_version": "63.0+build2-0ubuntu0.18.04.2", "binary_name": "firefox" }, { "binary_version": "63.0+build2-0ubuntu0.18.04.2", "binary_name": "firefox-dev" }, { "binary_version": "63.0+build2-0ubuntu0.18.04.2", "binary_name": "firefox-globalmenu" }, { "binary_version": "63.0+build2-0ubuntu0.18.04.2", "binary_name": "firefox-mozsymbols" }, { "binary_version": "63.0+build2-0ubuntu0.18.04.2", "binary_name": "firefox-testsuite" } ] }