CISA ALERT: Actively Exploited WhatsApp Zero-Day Lets Hackers Take Over Your App

On September 2nd, the U.S. Cybersecurity and Infrastructure Security Agency (CISA) added the vulnerability, identified as CVE-2025-55177, to its Known Exploited Vulnerabilities (KEV) catalog. This action confirms that the flaw is not just a theoretical risk—it is being actively used in real-world attacks right now.

Impact: A Tool for Espionage and Spyware

This is not a widespread, random attack. According to WhatsApp, this vulnerability was used as part of a highly targeted campaign to install spyware on the devices of fewer than 200 users. The attackers chained the WhatsApp flaw with another vulnerability in Apple's operating systems (CVE-2025-43300) to gain control of the targeted devices.thehackernews

The exploit is a "zero-click" attack, meaning a victim can be compromised without any interaction, such as clicking a link or downloading a file. The attack leverages an authorization bypass that allows a malicious actor to force a target's device to process content from an arbitrary URL. This level of sophistication is typically associated with well-resourced, state-sponsored threat actors like the previously reported Famous Chollima group, who use such tools for espionage and surveillance.securityaffairs+1

Actionable Steps: Update and Be Vigilant

Because this is a zero-day exploit that is actively being used, it is crucial for all users to take immediate action.

1. Update WhatsApp Immediately:

   • For iPhone/iPad: Go to the App Store, tap your profile picture at the top right, and pull down to refresh the updates list. Find WhatsApp and tap Update. The patched versions are v2.25.21.73 for WhatsApp and v2.25.21.78 for WhatsApp Business.whatsapp

   • For Mac: Open the Mac App Store, click on Updates in the sidebar, and update WhatsApp to version v2.25.21.78 or later.whatsapp

2. Be Wary of Unusual Activity: Even though this is a zero-click exploit, it's always wise to be cautious. Be suspicious of strange links, unexpected video calls, or unusual messages, even if they appear to come from a known contact whose account may have been compromised.

3. Enable Enhanced Security Measures: In WhatsApp, enable features like two-step verification and security notifications to add extra layers of protection to your account.

CISA has mandated that all U.S. federal agencies must apply the necessary patches by September 23, 2025, underscoring the seriousness of this threat. While the immediate targets appear to be specific individuals, all users should update their apps to protect themselves from potential future attacks leveraging this same vulnerability.

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