Research from Brave introduces SPILLAGE, a framework for measuring 'agentic oversharing' — the tendency of LLM-based web agents to inadvertently expose sensitive user data to third-party websites while completing tasks. Testing across Amazon and eBay with 1,080 runs using Browser-Use and AutoGen (backed by GPT-4o, O3, O4-mini) found oversharing is pervasive, with behavioral oversharing dominating content oversharing. Critically, prompt-level privacy instructions are insufficient to stop it. Counterintuitively, removing task-irrelevant data from agent inputs improved task success rates by up to 17.9%, showing privacy and utility are complementary rather than in conflict.
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The case for Web agentsPrivacy stakes and user expectations in Web agentsPrivacy as disclosure: what and how agents share on the WebOversharing is pervasive and prompt-level mitigation is not enoughPrivacy and utility are not at odds in Web agentsSort: