Google Warns 2 Billion Gmail Users: AI Summaries Hacked

September 18, 2025 - Cybersecurity & Compliance

Google warns 2 billion Gmail users about a sophisticated new cyber threat targeting AI email summaries. Hackers are embedding hidden instructions in emails, causing Google’s AI tools to generate fake alerts that trick users into calling fake support numbers, clicking malicious links, or giving away credentials.

This warning is a wake-up call for both individuals and businesses: AI can be misused to amplify phishing and fraud.

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What’s Going On: How AI Summaries Are Being Hacked

Researchers discovered that attackers are using a technique called indirect prompt injection. This involves embedding instructions into emails using hidden formatting such as white text on a white background or zero-size fonts that humans can’t see but Google’s AI reads when generating summaries.

When the AI “Summarize this email” feature is triggered, it follows these hidden commands. Victims may see summaries that look like official Google alerts: “Your account was compromised. Call this number now.”

• Forbes reported that over 2 billion Gmail users could be exposed.
• Tom’s Hardware analysis shows how AI can be manipulated with invisible instructions.

Who’s Affected

This issue impacts both personal Gmail users and organizations using Google Workspace. Any account that relies on AI summaries is at risk. With billions of Gmail accounts worldwide, the scale is enormous.

Businesses are especially vulnerable since employees may act quickly on warnings they believe come from Google.

Why This Matters

• Trust exploitation – Users trust Gmail summaries and may not question alerts that look official.
• Hidden manipulation – Malicious prompts are invisible to most people.
• New attack surface – AI features create new risks that traditional email filters don’t catch.
• Business exposure – Organizations with multiple Gmail accounts increase the attack surface for phishing campaigns.

What Google Is Doing

Google has confirmed the risk and is working on solutions:

• Updating Gemini AI to better detect hidden prompts.
• Improving filters for suspicious styling in emails.
• Providing user guidance about phishing risks linked to summaries.

Until fixes roll out, users need to remain cautious.

How to Protect Your Gmail Account

Zevonix recommends these immediate steps:

1. Don’t trust AI summaries blindly. If a summary says your account is hacked, verify by logging directly into Gmail or Google Account settings, never through links or phone numbers provided.
2. Turn on 2FA or passkeys. Strong authentication prevents most account takeovers.
3. Update Gmail apps. Make sure your Gmail app and browser are current with the latest patches.
4. Educate your team. Train employees to recognize suspicious summaries and report them.
5. Layered security. Consider professional security services to protect against phishing, spoofing, and AI-based threats.

👉 Learn how Zevonix protects businesses through our Managed IT Services and Cybersecurity Solutions.

Conclusion

Google’s warning shows that AI can be hacked just like any other system. The Gmail AI summary feature is convenient, but it’s also a new target for attackers. Businesses must recognize that the future of cybersecurity means defending not just networks and accounts, but also the AI tools that interpret them.

At Zevonix, we help organizations in Palm Coast, Jacksonville, St. Augustine, and Daytona Beach stay ahead of emerging threats. Don’t wait for a hack to test your defenses, let me help you strengthen them now.

📞 Call us at 904.658.0777
🔒 Book Your meeting with Zevonix »

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