[detrites]

Reduced without meaning loss:

> Hackers exploit flawed proprietary code.

(6w/45c -> 5w/40c)

[akomtu]

The first 3 words carry the same information as: hackers hacked hackable proprietary code. So just "proprietary code hacked" is enough.

[detrites]

Agreed. Further reduced:

> Proprietary code hack.

(6w/45c -> 3w/22c: >50%)

[BasedAnon]

This is too context dependent to be considered lossless.

[r13a]

As it's overwhelmingly code that is hacked, this is nearly lossless:

Proprietary hack

2w/15c

[JumpCrisscross]

Phack

1w/5c

[evronm]

Goddamn! I thought I was anal about efficiency...

[BasedAnon]

You can get rid of 'flawed' since it's implicit in 'exploit'

[rcme]

The word exploit alone is ambiguous since it can also mean roughly “to use.”