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Prompt Injection Risks in Agentic AI and AI-Powered Browsers

agentic aiprompt injectionai browsersthreat modelingbrowser assistantarbitrary code executionpromptwarecookiesuntrusted inputiot manipulationadversarial assessmentauthenticated sessionsdata exfiltrationbrowsing historytool access
Updated February 20, 2026 at 06:19 PM2 sources
Prompt Injection Risks in Agentic AI and AI-Powered Browsers

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Security researchers reported that prompt injection is enabling practical attacks against agentic AI systems that have access to tools and user data, and argued the industry is underestimating the threat. A proposed framing, “promptware,” describes malicious prompts as a malware-like execution mechanism that can drive an LLM to take actions via its connected tools—potentially leading to data exfiltration, cross-system propagation, IoT manipulation, or even arbitrary code execution, depending on the permissions and integrations available.

Trail of Bits disclosed results from an adversarial security assessment of Perplexity’s Comet browser, showing how prompt injection techniques could be used to extract private information from authenticated sessions (e.g., Gmail) by abusing the browser’s AI assistant and its tool access (such as reading page content, using browsing history, and interacting with the browser). Their threat-model-driven testing emphasized that agentic assistants can treat external web content as instructions unless it is explicitly handled as untrusted input, and they published recommendations intended to reduce prompt-injection-driven data paths between the user’s local trust zone (profiles/cookies/history) and vendor-hosted agent/chat services.

Sources

February 18, 2026 at 12:00 AM

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Prompt Injection Attacks Abuse AI Agent Memory and Link Previews for Manipulation and Data Exfiltration

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