Researcher finds security flaw in Gemini — but Google says it's not fixing it

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Although a researcher was able to demonstrate that Google Gemini could be tricked into giving users fake information like leading them to malicious websites, Google has said it doesn’t consider this ASCII smuggling attack a true security bug and it has no plans to issue a fix for the flaw.

As reported by BleepingComputer, the company dismissed the findings as being more of an issue of social engineering attacks than an actual security vulnerability.

ASCII smuggling is an attack style that uses special characters from the Tags Unicode block to introduce payloads that are invisible to users, but can still be detected and processed by large language models. – Essentially, this means that it hides letters, numbers or other characters to introduce malicious code to the AI assistant that users can’t see. LLMs have been vulnerable to ASCII smuggling attacks – and similar methods – for quite some time, however, the threat is now higher because agentic AI tools, like Gemini, have both widespread access to sensitive user data and can perform autonomous tasks.

According to the researchers “If users have LLMs connected to their inboxes, an email with hidden commands can instruct them [the AI] to search the inbox for sensitive items, send contact details and then turn a standard phishing attempt into an autonomous data extraction tool.” LLMs that have been told to browse websites could also potentially stumble onto hidden payloads in product descriptions and feed them with malicious URLs to feed back to users.

There are other techniques that use similar methods to manipulate the gap between what users see and what machines read including CSS manipulation and GUI limitations. The security researcher involved in this research found that Gemini, like Grok and DeepSeek, is vulnerable to ASCII smuggling attacks while Claude, ChatGPT and Microsoft Copilot are safe from such threats by implementing some form of input sanitization.

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Amber Bouman is the senior security editor at Tom's Guide where she writes about antivirus software, home security, identity theft and more. She has long had an interest in personal security, both online and off, and also has an appreciation for martial arts and edged weapons. With over two decades of experience working in tech journalism, Amber has written for a number of publications including PC World, Maximum PC, Tech Hive, and Engadget covering everything from smartphones to smart breast pumps.

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