In certain Arm CPUs, a CPP RCTX instruction executed on one Processing Element (PE) may inhibit TLB invalidation when a TLBI is issued to the PE, either by the same PE or another PE in the shareability domain. In this case, the PE may retain stale TLB entries which should have been invalidated by the TLBI.

Use of Hardware Page Aggregation (HPA) and Stage-1 and/or Stage-2 translation on Cortex-A77, Cortex-A78, Cortex-A78C, Cortex-A78AE, Cortex-A710, Cortex-X1, Cortex-X1C, Cortex-X2, Cortex-X3, Cortex-X4, Cortex-X925, Neoverse V1, Neoverse V2, Neoverse V3, Neoverse V3AE, Neoverse N2 may permit bypass of Stage-2 translation and/or GPT protection.

Spectre BHB is a variant of Spectre-v2 in which malicious code uses the shared branch history (stored in the CPU BHB) to influence mispredicted branches in the victim's hardware context. Speculation caused by these mispredicted branches can then potentially be used to cause cache allocation, which can then be used to infer information that should be protected.

A new cache speculation vulnerability known as Branch History Injection (BHI) or Spectre-BHB was found. Spectre-BHB is similar to Spectre v2, except that malicious code uses the shared branch history (stored in the CPU Branch History Buffer, or BHB) to influence mispredicted branches within the victim's own hardware context. Once that occurs, speculation caused by mispredicted branches can be used to cause cache allocation, which can then be used to infer information that should not be accessible.