What security impact of the Haswell/early-Broadwell TSX bug? The support for all TSX instructions where really disabled by the microcode update, and we know that for sure because it crashed the world instantly (in Linux).

Now, working TSX can have a security impact, yes. At least on TSX as implemented on later Broadwell/early Skylake, memory accesses done from inside an speculative region are allowed to bypass stuff they shouldn't. Is that what you meant?