A mechanism was discovered in Firefox before 66.0 that removes some bounds checking for string, array, or typed array accesses if Spectre mitigations have been disabled. This vulnerability could allow an attacker to create an arbitrary value in compiled JavaScript, for which the range analysis will infer a fully controlled, incorrect range in circumstances where users have explicitly disabled Spectre mitigations. Note that Spectre mitigations are currently enabled for all users by default settings.
A mechanism was discovered in Firefox before 66.0 that removes some bounds checking for string, array, or typed array accesses if Spectre mitigations have been disabled. This vulnerability could allow an attacker to create an arbitrary value in compiled JavaScript, for which the range analysis will infer a fully controlled, incorrect range in circumstances where users have explicitly disabled Spectre mitigations. Note that Spectre mitigations are currently enabled for all users by default settings.
https://www.mozilla.org/en-US/security/advisories/mfsa2019-07/#CVE-2019-9793 https://bugzilla.mozilla.org/show_bug.cgi?id=1528829
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