When performing EC scalar point multiplication, the wNAF point multiplication algorithm was used; which leaked partial information about the nonce used during signature generation. Given an electro-magnetic trace of a few signature generations, the private key could have been computed. This vulnerability affects Firefox < 80 and Firefox for Android < 80.
https://bugzilla.mozilla.org/show_bug.cgi?id=1631583
https://lists.debian.org/debian-lts-announce/2023/02/msg00021.html