“Future Claude models will generate text that contains a watermark. This is a way of determining the likelihood that Claude was involved in writing the text, and we, along with several other major AI providers, are implementing this change to comply with the EU AI Act.”
Category: Claude
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“Severe cybersecurity vulnerability disclosures (CVEs) spiked in 2026. In June, notable organizations published around 1,500 high- and critical-severity CVEs — more than 3.5× the monthly record prior to Mythos’ release.”
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- Long-running work: It can work for hours on a task, recovering from errors and routing around blockers instead of stopping. It also checks its own work as it goes and catches issues that earlier models missed. It reaches 43.3% on Frontier-Bench v0.1 and 68.8% on DeepSWE v1.1 (up from 18.7% / 59.0% on Opus 4.8).
- It more regularly asks clarifying questions before guessing, pushes back on flawed instructions, and considers the implications of its work before jumping ahead to implementation. The result is cleaner, higher-quality code.
“Opus 5 does not advance the frontier in risky, dual-use capabilities. In rigorous evaluations conducted alongside private-sector and government partners, we found it remains behind Mythos 5 in both biology research and offensive cybersecurity.
As with its predecessor, Opus 4.8, we’ve intentionally avoided training Opus 5 on cyber tasks. Opus 5’s cyber classifiers are proportionally less restrictive than those on Fable 5. They allow Opus 5 to find vulnerabilities in source code, but block “binary-based” vulnerability scanning, penetration testing, and exploit generation.”
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“Starting July 20, Claude Fable 5 is included in all Max and Team Premium plans at 50% of usage limits, and Claude Code’s 50% higher weekly rate limits run through August 19. /code-review gained effort levels plus an ultra tier, artifacts went multiplayer with MCP connectors, and the MCP 2026-07-28 spec RC drops session pinning entirely.”
/root 