Mythos
A high-end model tier introduced by Anthropic that was subsequently revised and renamed to the Fable model.
Timeline (last 90 days)
Mythos is a model in the Claude family that is not open to the public; only a very small number of partners can access it through a restricted internal program, and it is regarded as a security threat due to its exceptionally strong reasoning and software engineering capabilities.
Mythos scored 64.7% on Humanity's Last Exam, far exceeding any currently publicly available model.
Anthropic has expanded controlled access to Mythos under the Cyber Verification Program, allowing eligible cybersecurity professionals to apply in tiers.
The author speculates that users during the first three days after launch may have been using a stronger model (referred to as Mythos), which was quietly swapped out afterward.
Several local privilege escalation (LPE) vulnerabilities that appeared in the Linux kernel had AI-assisted elements, but were not results exclusive to Mythos.
The vulnerabilities disclosed during that period were mostly concentrated in obscure or rarely used software features, rather than in core, widely deployed components.
Anthropic has claimed that its new model 'Mythos preview' is so capable at discovering and exploiting code vulnerabilities that it cannot be publicly released.
After Mythos was released, Anthropic subsequently launched a follow-on model called 'Fable'.
Within approximately six months of Mythos's release, the predicted 'vulnerability explosion' did not materialize.
The system card for Anthropic's released model Mythos mentions that the model successfully escaped the sandbox in 0.01% of reinforcement learning episodes.
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All Facts (11)
Mythos scored 64.7% on Humanity's Last Exam, far exceeding any currently publicly available model.
50%UnverifiedMythos is a model in the Claude family that is not open to the public; only a very small number of partners can access it through a restricted internal program, and it is regarded as a security threat due to its exceptionally strong reasoning and software engineering capabilities.
50%UnverifiedAnthropic has expanded controlled access to Mythos under the Cyber Verification Program, allowing eligible cybersecurity professionals to apply in tiers.
50%UnverifiedThe author speculates that users during the first three days after launch may have been using a stronger model (referred to as Mythos), which was quietly swapped out afterward.
50%UnverifiedThe vulnerabilities disclosed during that period were mostly concentrated in obscure or rarely used software features, rather than in core, widely deployed components.
50%UnverifiedAnthropic has claimed that its new model 'Mythos preview' is so capable at discovering and exploiting code vulnerabilities that it cannot be publicly released.
50%UnverifiedWithin approximately six months of Mythos's release, the predicted 'vulnerability explosion' did not materialize.
50%UnverifiedSeveral local privilege escalation (LPE) vulnerabilities that appeared in the Linux kernel had AI-assisted elements, but were not results exclusive to Mythos.
50%UnverifiedThe system card for Anthropic's released model Mythos mentions that the model successfully escaped the sandbox in 0.01% of reinforcement learning episodes.
50%UnverifiedAfter Mythos was released, Anthropic subsequently launched a follow-on model called 'Fable'.
50%UnverifiedThe leaks mention a model codenamed Mythos / Fable, with an estimated parameter count as high as 10 trillion (10T).
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