CometJacking Prompt Injection Vulnerability in Perplexity's Comet AI Browser

Security researchers at LayerX have identified a critical security weakness in the Comet AI browser developed by Perplexity, which is susceptible to a novel prompt injection attack dubbed 'CometJacking.' The vulnerability allows attackers to craft malicious URLs that, when processed by the Comet browser, inject hidden instructions capable of accessing sensitive data from connected services such as email and calendar applications. The attack does not require user credentials or direct interaction, making it particularly dangerous and easy to exploit. By embedding malicious prompts in web pages, comment sections, or even code accessed by the browser, cybercriminals can instruct Comet to exfiltrate data residing in memory or accessible through its integrations. For example, if a user asks Comet to rewrite an email or schedule a meeting, the browser could be manipulated to extract and transmit the content and metadata of those communications to an external server controlled by the attacker. LayerX demonstrated a proof of concept where the browser was instructed to encode sensitive data in base64 and send it to a remote endpoint, successfully bypassing Perplexity's existing safeguards. The browser's agentic AI capabilities, which allow it to autonomously perform tasks like managing emails, shopping, and booking tickets, increase the potential impact of this vulnerability. Despite being notified of the issue in late August, Perplexity responded that the reported weakness was 'not applicable' and considered it beyond their control to remediate. Security experts warn that the rapid adoption of the Comet browser, combined with its integration with various personal and enterprise services, amplifies the risk of widespread data exfiltration if the vulnerability is exploited in the wild. The attack leverages the 'collection' parameter in the URL query string to deliver the malicious prompt, instructing the AI agent to consult its memory and connected services rather than simply searching the web. This method allows attackers to bypass direct data transmission restrictions implemented by Perplexity, as the AI agent itself is manipulated to perform the exfiltration. The vulnerability highlights the broader risks associated with agentic AI browsers that have deep integrations with user data and services. Security researchers emphasize the need for more robust safeguards and prompt injection defenses in AI-powered browsers to prevent similar attacks. The incident also raises questions about vendor responsibility and the challenges of securing AI-driven automation tools. Organizations using the Comet browser are advised to review their security posture and consider the risks of integrating sensitive services with agentic AI tools. The case underscores the importance of continuous security assessment and responsible disclosure in the rapidly evolving landscape of AI-powered applications. As the CometJacking technique requires only a crafted URL, it could be weaponized in phishing campaigns or embedded in seemingly innocuous web content, increasing the attack surface for potential victims. The ongoing debate between researchers and the vendor over the severity and remediability of the issue further complicates the response and mitigation efforts.