Using writable media is the biggest security vulnerability.

[xor]

Using writable media is the biggest security vulnerability.

The native structure of operating system files is 99.99% read-only.
In this respect, uploading it to a writable media platform is nonsense!
if you really care about data security
it is recommended to use SD-cards with physical write protection

if you are using multiple operating systems
Review multi-iso boot usb options.

[hiro]

sadly, sd cards are actually not physically write protected.
it's a physical switch that is read and enforced only by the sd card reader or OS.

[nick65go]

As a matter of facts, nothing is secure. ex: even ISO loaded into RAM  could be "modified"/patched on the fly. So, with bugs in CPU, firmware/UEFI, in OS, in filesystem, in programs, etc, do you expect a "secure" environment?

Repeat after me (please) until you will believe it: security is an illusion, as long as you do not fully "own" something: you do not compile it, understand the source, AND you build the compiler (trust the trustee) , etc etc.

And then you use "other's" infrastructure (google) and ISP (without VPN). Oh boy ... the biggest security flaw is the human user.Most people already choose (wrongly !) the comfort/laziness instead of better security. The resistance is futile.

[gadget42]

ditto(what @nick65go said)