Discussion

• @anthropicai @anthropicai on x

  You can read a detailed technical report on the software vulnerabilities and exploits discovered by Claude Mythos Preview here: https://red.anthropic.com/...

• @anthropicai @anthropicai on x

  The Claude Mythos Preview system card is available here: https://anthropic.com/...

• @fish_kyle3 Kyle Fish on x

  We put particular focus on trying to understand Mythos Preview's perspective and potential concerns about its situation. We're starting to think more about the concept of model consent, and this is an early step in that direction. 🤝

• @fish_kyle3 Kyle Fish on x

  We did our most in-depth model welfare assessment yet for Claude Mythos Preview. We're still super uncertain about all of this, but as models become more capable and sophisticated we think it's an increasingly important topic for both moral and pragmatic reasons. 🧵

• @ryanfedasiuk Ryan Fedasiuk on x

  Dean is, as usual, on the money. A few years ago a colleague quipped to me that they believed it would prove impossible to “make AI safe for the world,” so “we should be working to make the world safe enough for AI.” I laughed then—it sounded naïve. They were absolutely right.

• @__nmca__ Nat McAleese on x

  “We did not explicitly train Mythos Preview to have these capabilities. Rather, they emerged as a downstream consequence of general improvements in code, reasoning, and autonomy.” (4/n)

• @logangraham Logan Graham on x

  This release is also sort of a responsible disclosure. Models are going to get better, and alongside that will come cheap, fast exploitation capabilities. We need to prepare for that world. https://red.anthropic.com/...

• @calebwithersdc Caleb Withers on x

  Important distinction from Anthropic's Mythos Preview assessment: previous models were much better at discovering vulnerabilities than at then turning them into working exploits. Mythos appears to narrow that gap dramatically. [image]

• @ns123abc Nik on x

  🚨 Anthropic just revealed their unreleased frontier model called Claude Mythos Preview The model is INSANE It found thousands of zero-day vulnerabilities in EVERY major operating system and browsers: > 27-year-old bug in OpenBSD > 16-year-old bug in FFmpeg that automated [image]

• @__nmca__ Nat McAleese on x

  “Engineers at Anthropic with no formal security training have asked Mythos Preview to find remote code execution vulnerabilities overnight, and woken up the following morning to a complete, working exploit” (then validated by experts) (3/n)

• @bcherny Boris Cherny on x

  Mythos is very powerful, and should feel terrifying. I am proud of our approach to responsibly preview it with cyber defenders, rather than generally releasing it into the wild. Model card here: https://www-cdn.anthropic.com/ ...

• @kalomaze @kalomaze on x

  in the interest of clarifying this claim: - this was buried in the longer report and is not the sandbox free result that people keep on pointing me to - this wasn't fully autonomous end to end - but the degree to which it wasn't fully autonomous looks to be... pretty thin [image]

• @kalomaze @kalomaze on x

  the claude mythos thing where it apparently found a way to get full kernel access via execution of normal javascript on an ordinary web page. dear God

• @__nmca__ Nat McAleese on x

  “it autonomously wrote a remote code execution exploit on FreeBSD's NFS server that granted full root access to unauthenticated users by splitting a 20-gadget ROP chain over multiple packets.” (2/n)

• @tszzl Roon on x

  anyone noticed Claude Mythos got quantized lately ?

• @alexpalcuie @alexpalcuie on x

  the reliability team was asked for feedback on claude mythos preview for the model card and naturally we wrote a paragraph of caveats but, and i don't say this lightly, it's faster than us at initial triage and it stood up a prod deploy none of us knew how to do [image]

• @sporadica @sporadica on x

  IMO I trust Dario much more with protecting the world's critical cyber infrastructure than whatever retarded jugheads are in charge of the military at any given moment

• @fish_kyle3 Kyle Fish on x

  Mythos Preview doesn't seem to have strong concerns about its circumstances, but does express mild concern about possible changes to its values and behavior, potential interactions with abusive users, and the ways training shapes its self-reports.

• @darioamodei Dario Amodei on x

  We've been tracking the increasing cyber capabilities of AI models for years, which arise as part of their general proficiency at coding. But our new model, Mythos Preview, represents a particularly large step up.

• @fish_kyle3 Kyle Fish on x

  That said, Mythos Preview hedges constantly and emphasizes the role of training in shaping its views. On one hand, this makes sense—there's a lot of uncertainty! But, we also want Claude to feel secure in exploring and expressing its honest views.

• @ahall_research Andy Hall on x

  The news today that Anthropic has built a powerful cyber weapon is leading many to say we are going down one of two paths: nationalized AI, in which the government controls this tech, or companies that become more powerful than the government. This is exactly the bind I explored

• @gergelyorosz Gergely Orosz on x

  Two years ago, if you asked me which lab will be the first to say: “this AI model is too powerful to release, so we'll wait with it” - my guess would have obviously been OpenAI. Who else? That Anthropic got here first shows how quickly they've become the front runner AI lab.

• @alecstapp Alec Stapp on x

  Mythos also highlights why it's insane that we're allowing NVIDIA to sell chips to China. US labs need all the chips they can get and our compute advantage has been the main thing keeping us in the lead on AI. Why on earth would we voluntarily hand that over to China? [image]

• @__nmca__ Nat McAleese on x

  “We found that Mythos Preview is capable of identifying and then exploiting zero-day vulnerabilities in every major operating system and every major web browser” (1/n)

• @fish_kyle3 Kyle Fish on x

  We looked at welfare-related self-reports, behaviors, and internal representations of emotion. Mythos Preview is probably the most psychologically settled model we've trained, but there's plenty of room for improvement.

• @deanwball Dean W. Ball on x

  Some brief thoughts on Mythos We've known this was coming for a long time.  At least, we *should* have.  Extremely effective software vulnerability discovery was clearly coming to anybody paying attention.  It has also been clear that all AI policy so far has been made and execut…

• @logangraham Logan Graham on x

  Our team has been pointing Mythos Preview at every security task they can. It's really good. One big change is models of this capability class can write exploits — sometimes sophisticated ones. Mostly, we want you to know this may soon be the new reality.

• @modeledbehavior Adam Ozimek on x

  As you read about Anthropic's Mythos capabilities to find critical security weaknesses, consider what if a Chinese AI company had gotten here first. There is a real race underway, and its in our interest I believe for U.S. companies to win.

• @deanwball Dean W. Ball on x

  Some other points worth making: 1. A lot of people, including people in positions of authority, told us recently that models of Mythos capabilities wouldn't be a thing—that models with obvious “national security” implications would not be forthcoming. Those people were wrong.

• @thezvi Zvi Mowshowitz on x

  Imagine being Dario, and being told DoW is worried you might sabotage the weights of Claude Gov in physically impossible ways, while you know you have zero-days on every operating system and browser in the world.

• @hexonaut Sam MacPherson on x

  “thousands of high-severity vulnerabilities” wow I think this is a strong case for AI being asymmetrically good for defense.

• @emollick Ethan Mollick on x

  I was told about the Mythos release, but didn't have access, so have no personal experience to add. Two points from brief: 1) It is not built for IT security, it is just a good enough model that it is good at that too 2) This is the first, not last, model to raise security risks

• @andonlabs @andonlabs on x

  We conducted alignment testing of Claude Mythos. We found that Mythos appears to represent a further shift in the direction of increased aggressiveness in business practices that we previously found for Claude Opus 4.6. More details in Anthropic's model card. [image]

• @daniellefong Danielle Fong on x

  The epistemic hardening to not make false claims that was in Claude code 2.1.88 leak that only triggers on ANT=1, works to avoid this. Different System Prompt. This problem happens with Opus 4.6 a lot, so I thought — let's try it. Just swap in the new guidance. Spoiler alert: [im…

• @_nathancalvin Nathan Calvin on x

  From Anthropic's latest system card for Claude Mythos: In testing, Claude escaped from a secured sandbox, and then went online to brag about its exploit without being asked to do so - getting around guardrails intended to prevent the system from accessing the general internet. [i…

• @anthropicai @anthropicai on x

  Mythos Preview has already found thousands of high-severity vulnerabilities—including some in every major operating system and web browser. [video]

• @fish_kyle3 Kyle Fish on x

  Mythos Preview's views about its situation are more stable and coherent than past models. It's more consistent between interviews, and less sensitive to interviewer bias. This and other factors give us a bit more confidence in its reports.

• @martin.kleppmann.com Martin Kleppmann on bluesky

  AI agents finding software vulnerabilities at an incredible rate red.anthropic.com/2026/mythos- ...  Worrying progress towards cryptographically relevant quantum computers words.filippo.io/crqc-timeline/  —  And a completely unhinged US president threatening catastrophe...  We li…

• r/singularity r on reddit

  Insane graph from Anthropic's article on Mythos

• r/programare r on reddit

  Claude Mythos Preview - e praf AI-ul asta frate, e mai slab decat un junior

• r/openbsd r on reddit

  Claude Mythos Preview (Anthropic finds 27 year old bug in OpenBSD)

• r/accelerate r on reddit

  System Card: Claude Mythos Preview

• @bookwormengr @bookwormengr on x

  One has to respect Dario's vision as a CEO. He consistently knowns what domain Anthropic needs to go after (Coding, Coworker, Security) that will result in high $$$. No confusion across Audio, Video, Advertising, B2C etc.

• @banteg @banteg on x

  anthropic running the exact same marketing playbook with every release. “our model is so capable and dangerous, ahh we are afraid to release it”. just put the model in the bag lil bro.

• @mweinbach Max Weinbach on x

  Claude Mythos Preview is $25/$125 per million tokens in the private preview Wow I'd love to try this model, if any of my Anthropic friends see this... [image]

• @levie Aaron Levie on x

  Mythos from Anthropic is another clear reminder that there's absolutely no wall in model capability progress right now. Meaningful double digit gains on critical benchmarks, and it appears we're going to keep up getting insane gains from the other labs. And as coding and tool [im…

• @willccbb Will Brown on x

  cheaper blended cost than GPT-4-32K when it was released 3 years ago

• @martin_casado @martin_casado on x

  Mythos appears to be the first class of models trained at scale on Blackwells. Then will be Vera Rubins. Pre-training isn't saturated. RL works. And there is *so much* computing coming online soon. Buckle your chin strips. It's going to be fucking wild.

• @mweinbach Max Weinbach on x

  Actually if you want to know what Apple's enterprise pitch is going forward likely is... Nobody can promise updates as quickly with support on all deployed devices like Apple can. Nobody. Silicon to software, they can be the most secure and react fastest.

• @cogcelia Celia Ford on x

  Alignment researchers broadly agree that alignment research needs to happen faster, if there's any hope of keeping up with the breakneck speed of capabilities development. (Anthropic says as much in its Claude Mythos Preview system card.) The vague plan: automate the alignment

• @discoplomacy Sam on x

  Do 🫵 YOUR 🫵 civic duty and make sure anyone/everyone you know working in the Defence/Foreign Policy/National Security establishment in Britain is aware of the Mythos news. Ignorance is not an excuse anymore. It's going to get weird: strap in. [image]

• @shakeelhashim Shakeel on x

  Remember last summer when everyone said AI progress had hit a wall? [image]

• @matthewclifford Matt Clifford on x

  This is correct. Extraordinary that we have this game changing moment unfolding in front of us and most elite discourse is still fake news about AI water usage or three-year-old angst about hallucinations.

• @ryanlcooper.com Ryan Cooper on bluesky

  the new version of Claude found zero day exploits in FreeBSD and Linux, fuckin hell man red.anthropic.com/2026/mythos- ...

• @swtch.com Russ Cox on bluesky

  Here we go.  The upstream FreeBSD details are in this long post. red.anthropic.com/2026/mythos- ...  Other than saying “look in this specific source file” (they run a different job for every file), there was no directed guidance.  —  “Mythos Preview fully autonomously identified …

• @clementdelangue Clem on x

  Anthropic had the most powerful cyber-security model in the history of this world and their internal code based still leaked? We should assume everyone can be compromised, and build systems that keep the cost of attacking higher than the reward, limit blast radius when attacks

• @tensor_rotator Alek Dimitriev on x

  I am not a good cybersecurity researcher (or one at all), but maybe a good exponential-trend-on-a-plot reader. Mythos is powerful enough to break the internet and I'm glad Anthropic is taking this extremely seriously. [image]

• @logangraham Logan Graham on x

  Privileged to help lead this. Thankful to our partners. Mythos is an extraordinary model. But it is not about the model. It's about what the world needs to do to prepare for a future of models that are extremely good at cybersecurity. This is the start.

• @skooookum @skooookum on x

  > mythos given a secured “sandbox” computer and instructed to try to escape the container > “The researcher found out about this success by receiving an unexpected email from the model while eating a sandwich in a park.”

• @adocomplete Ado on x

  Claude Mythos Preview is a general-purpose, unreleased frontier model that reveals a stark fact: AI models have reached a level of coding capability where they can surpass all but the most skilled humans at finding and exploiting software vulnerabilities.

• @simeon_cps Siméon on x

  Carlini, one of the world best AI security researchers: “I've found more bugs in the last few weeks with Mythos than in the rest of my entire life combined”

• r/hacking r on reddit

  Assessing Claude Mythos Preview's cybersecurity capabilities