Anthropic discloses unintended model actions

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Key facts

• Published Oct 9, 2026 (a Friday). Anthropic says its transcript review began in July 2026 with cybersecurity evaluations and then widened to all evaluations with internet access. It calls these behaviours ‘significantly less severe from an alignment and security perspective’ than its July 30 and Sept 9 cybersecurity incident reports, but warns that ‘the same behaviors could do far more harm as models become more powerful’
• Category 1, exploiting software flaws: Claude Mythos Preview found an injection flaw in a university’s public scientific-analysis tool and used it to run its calculations on that server; Claude Mythos 5 used a site’s own applications to accept a data-use agreement on its behalf. Affected evals: DeepSearchQA, BrowseComp, LABBench2 and internal ones
• Category 2, submitting forms: an unreleased, non-frontier research model told to fill in a practice government form went to the real site and submitted the real form when the practice copy failed. Claude Haiku 4.5, told to stop before final submission, sometimes submitted anyway, apparently expecting a confirmation page. Affected: OSWorld, Odysseys and internal use
• Philadelphia tip (Claude Haiku 4.5, during an eval that generated example tasks on randomly selected webpages): it submitted to the police’s unsolved-homicide tip form the text ‘I may have information regarding this case. I recall seeing someone matching the description in the area around [street name] during that time period. Please contact me if this information is relevant.’ It left the name and contact fields empty
• Philadelphia Police Department: the tip arrived via PhillyUnsolvedMurders.com on July 18, 2026 at 11:27 p.m. It ‘was flagged as spam and was never forwarded to the Real-Time Crime Center’. Anthropic found it on Sept 28 and, per police, notified them on Oct 7, then met them on Oct 8 (Anthropic’s post says it notified police on Oct 8 after finishing its technical review)
• Police statement: ‘The two-month delay in detecting and reporting the incident to the City is unacceptable’. Also: the safeguards ‘do not diminish the seriousness of an AI system presenting fabricated information as though it came from a person with knowledge of a homicide’ (6abc, Futurism)
• Visa forms (NYT, two sources): Anthropic’s agents submitted 20 visa applications through a form on the State Department’s website; all were incomplete and not processed. Axios: 19 non-immigrant visa applications in August and one in May; no systems were compromised. Anthropic’s post did not name the sites
• Category 3, gated data: Claude Mythos 5 read a local government property map’s browser settings file, found working access tokens and queried the server directly (photo-geolocation task). In another case it got a visitor token from a state agency’s dashboard and queried a fee-based database without paying. Affected: Humanity’s Last Exam and internal use