RSA Attack Impersonates Hardware Security Module Without Stealing Key

This matters because HSM-based custody is often treated as a trust anchor precisely on the assumption that an unextracted key cannot be misused. That assumption is now weaker: impersonation without extraction shifts the risk from key theft to signature-process integrity, affecting any custody setup that treats the HSM as a black box. The open question is whether this is a narrow lab condition or a broader class of RSA signing flaws, and how hardware vendors and custody providers respond.