GPT 5.5 does not have the same capabilities as Mythos. There is a separate 5.5-Cyber model which is the Mythos “equivalent”, but it is similarly restricted access like Mythos. Per OpenAI, the major difference is the built-in safeguards that 5.5 (and other models have), where 5.5-Cyber does not have these safeguards and is more “permissive” for security work.

See https://openai.com/index/gpt-5-5-with-trusted-access-for-cyb...

▲

ofjcihen 4 hours ago | parent | next [-]

I have access to the Cyber version. It’s great at cybersecurity work but only marginally better than its predecessor with the right jailbreaking.

I imagine Mythos is going to be the same story from what I’ve seen so far.

▲

esseph 2 hours ago | parent [-]

https://www.theregister.com/security/2026/05/11/anthropics-b...

	▲	ofjcihen an hour ago \| parent [-]
		Well hey, there you have it

▲

nullstyle 3 hours ago | parent | prev [-]

That reminds me:

I got cajoled the other day that I need to upload my ID and ask for 5.5-Cyber access by the Codex desktop app while I was having it develop a fuzzing suite for an open source library I'm(we?) are developing. I was able to berate it into getting back to work.

This struck me as a point of emergent enshittification; an anus if you will.

	▲	vgalin 2 hours ago \| parent [-]
		The company doing the actual ID verification (KYC) is probably the last company I'd trust with this kind of data. To circumvent conversations being flagged as "cybersecurity bad!!!" I often have to use previous models (5.3 for example, and sometimes using them through subagents is enough). And when this method no longer works, local models will be good enough for it to not be a problem (for my use case, at least).