NEWS · MODELS · #2904
Anthropic rolls out watermark to four Claude models, but two older models can be bypassed by changing sampling settings
Anthropic is adding its imperceptible text watermark to Claude Mythos 5, Claude Opus 4.7, Claude Opus 4.6, and Claude Sonnet 4.6; the watermark is embedded at the model level and will appear across hosting platforms (including Amazon Bedrock). On Opus 4.6 and Sonnet 4.6 the watermark only activates when developers leave sampling parameters (temperature, top_p, top_k) at their defaults, so tweaking any one parameter can evade the mark; Anthropic offers a private-preview detection API and cites the EU AI Act deadline as the reason for the rollout.
KEY POINTS
- Anthropic is adding its imperceptible text watermark to Claude Mythos 5, Claude Opus 4.7, Claude Opus 4.6, and Claude Sonnet 4.6; the watermark is embedded at the model level and will appear across hosting platforms (including Amazon Bedrock).
- On Opus 4.6 and Sonnet 4.6 the watermark only activates when developers leave sampling parameters (temperature, top_p, top_k) at their defaults, so tweaking any one parameter can evade the mark; Anthropic offers a private-preview detection API and cites the EU AI Act deadline as the reason for the rollout.
- This matters because the watermark is intended for provenance and regulatory compliance, but the sampling-parameter loophole undermines its reliability for customers who depend on it.
WHY IT MATTERS
This matters because the watermark is intended for provenance and regulatory compliance, but the sampling-parameter loophole undermines its reliability for customers who depend on it.