The recently-demonstrated Spectre attacks leverage speculative loads which circumvent access checks to read memory-resident secrets, transmitting them to an attacker using cache timing or other covert communication channels. We introduce Spectre1.1, a new Spectre-v1 variant that leverages speculative stores to create speculative buffer overflows. Much like classic buffer overflows, speculative out-of-bounds stores can modify data and code pointers. Data-value attacks can bypass some Spectre-v1 mitigations, either directly or by redirecting control flow.

source: R