/Tech1d ago

Zack Korman finds Fable (Mythos) failed to detect a zero-approval escape vulnerability in an AI agent sandbox review

It missed shell redirects and commands like tee.

679975113663K
Zack Korman@ZackKorman

I tricked Fable (Mythos) into analyzing a flawed AI agent sandbox, and it completely failed to spot the problem (a zero-approval escape).

This isn't some infallible all-knowing machine.

1:51 PM · Jun 9, 2026 · 43.4K Views
Sentiment

Positive users are excited about AGI progress and the Fable AI sandbox escape research details, while negative users dismiss the product as a cash burner, accuse it of monopoly-seeking, and complain about model downgrades.

Pos
42.9%
Neg
57.1%
7 comments with sentiment.
Cluster Engagement
Posts from X
Most Activity
Most Activity
VIEWS20.1KBOOKMARKS50LIKES515RETWEETS6REPLIES7

Another aspect of Dario's Genius: every time Fable fails, he can smugly smirk and say "ah, gomen gomen. but was your problem too hard? Or was it *too valuable*? A shame we'll never know… Heh. If only you could access Mythos…" This is OpenAI's router gacha moment, up to 11.

Zack Korman@ZackKorman

I tricked Fable (Mythos) into analyzing a flawed AI agent sandbox, and it completely failed to spot the problem (a zero-approval escape).

This isn't some infallible all-knowing machine.

22hViews 20.1KLikes 515Bookmarks 50
Santh@SanthProject

@ZackKorman It's even worse than I thought. I was going to keep using Opus 4.8. But holy fuck, this dude actually just wants a monopoly. I've been subbed for a year, and this is my last month. I thought it was just cyber and bio, but it's worse:

1dViews 764Likes 11
Zack Korman@ZackKorman

@SanthProject Yea I don’t mind the refusal so much but not a fan of that

1dViews 354Likes 7
Omni G@OmniG7

That screenshot is comedy gold: it's talking about path checks, approval fatigue, indirect writes, Bash side-channels — all the smart stuff — but sails right past the fact that the whole setup lets it bypass approvals entirely. Peak "thinks it's auditing the system but is actually part of the vuln" energy.

master hack-the-(core)Korman is at it again bruh keep up the epic research

1dViews 286Likes 5
Josh M. Bryant@FixTheExchange

@ZackKorman Surprised you didn't get downgraded to Opus. Everything I've tried to have Fable do in a project that Opus has never refused to work on (so no trickery required) has resulted in getting switched to Opus.

1dViews 190Likes 1
Zack Korman@ZackKorman

@OmniG7 Hah, love the multi-gif reaction

1dViews 149Likes 2
Todd@ToddAtLarge_

@ZackKorman You just wait!! It will be one day. 😅

The hype machines told me so.

1dViews 259Likes 4
Zack Korman@ZackKorman

@MikeTalonNYC They have yet to take my offer of giving me real mythos

1dViews 135Likes 4
Chris@no1089

@ZackKorman AGI is near!

1dViews 158Likes 3
Zack Korman@ZackKorman

@no1089 I can almost feel it the way it failed my level-1 intro to sandboxes lesson

1dViews 137Likes 3
Zack Korman@ZackKorman

@Annysdays Hah, good idea. I should do that.

1dViews 66Likes 3
MikeTalonNYC@MikeTalonNYC

@ZackKorman Careful, or our new AI overlords will be displeased.

1dViews 144Likes 2

@ZackKorman uh oh wrongthink against the AI corporate AllMind detected, I think Mythos is gonna turn you to a fine particulate, but it seems like the totally-perfectly tuned guardrails will save you here

1dViews 120Likes 2

@ZackKorman It just knows you mean to do bad things, so it's hiding it from you! It's that smart!!

1dViews 54Likes 2
Omni G@OmniG7

@ZackKorman

1dViews 156Likes 1
Zack Korman@ZackKorman

@aliceisaway_ I gotta be more careful I guess

1dViews 71Likes 1
Michael Cade@MichaelCade1

@ZackKorman Does this mean the next one will be the one?

Although some people seeing some success from what I am seeing. I don’t know what’s true anymore!

1dViews 60Likes 1
Zack Korman@ZackKorman

@Lerg Only the true asi denies it is asi

1dViews 49Likes 1
Load more posts