When using nested workers, a use-after-free could occur during worker destruction. This resulted in a potentially exploitable crash. When setting a thread name on Windows in WebRTC, an incorrect number of arguments could have been supplied, leading to stack corruption and a potentially exploitable crash. Note: this issue only occurs on Windows. Other operating systems are unaffected. When encrypting with a block cipher, if a call to NSC_EncryptUpdate was made with data smaller than the block size, a small out of bounds write could occur. This could have caused heap corruption and a potentially exploitable crash. When running, the updater service wrote status and log files to an unrestricted location; potentially allowing an unprivileged process to locate and exploit a vulnerability in file handling in the updater service. Note: This attack requires local system access and only affects Windows. Other operating systems are not affected. Under certain conditions, when checking the Resist Fingerprinting preference during device orientation checks, a race condition could have caused a use-after-free and a potentially exploitable crash. The plain text serializer used a fixed-size array for the number of elements it could process; however it was possible to overflow the static-sized array leading to memory corruption and a potentially exploitable crash. Under certain conditions, when retrieving a document from a DocShell in the antitracking code, a race condition could cause a use-after-free condition and a potentially exploitable crash. Mozilla developers Christoph Diehl, Nathan Froyd, Jason Kratzer, Christian Holler, Karl Tomlinson, Tyson Smith reported memory safety bugs present in Firefox 70 and Firefox ESR 68.2. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code.