The new version of the ESP32 system on chip is secure, it has fixed the fault injection vulnerability found on earlier versions, here’s what Espressif say about it:
Fixed Fault injection issues regarding secure boot and flash encryption are fixed.
Reference: Security Advisory concerning fault injection and eFuse protections
(CVE-2019-17391) & Espressif Security Advisory Concerning Fault Injection and Secure
Boot (CVE-2019-15894)