Malware via Message? CERT-In Flags Major WhatsApp Desktop Security Bug

CERT-In and Meta confirm vulnerability; no active exploits reported yet

In a major security alert, India’s national cyber agency CERT-In has found a critical flaw in WhatsApp’s desktop app for Windows that allows an attacker to attack them via a message attachment with exploit code. This basic flaw shows that even the most trusted apps can be used to attack unsuspecting users.

Vulnerability CVE-2025-30401

The CVE identified as CVE-2025-30401 is a spoofing vulnerability in WhatsApp Desktop versions less than or equal to 2.2450.6. The issue is about how the app chooses to open a file based on the file name extension, regardless of the file’s actual media type (i.e., what the file’s MIME type is). This created a window of opportunity for an attacker to execute malicious code on the user’s machine.

“WhatsApp for Windows Version 2.2450.6 and prior displayed attachments according to their MIME type but selected the file opening handler based on the attachment’s filename extension,” said WhatsApp in a public advisory. “A maliciously crafted attachment could cause the recipient to unknowingly execute arbitrary code.”

How It Works: A Sneaky Trick

In reality, this vulnerability allows threat actors to send users what looks like a harmless attachment—a PDF file—but is actually an executable file disguised to look safe. If a user opens the file manually in WhatsApp, it will trigger a code execution process that gives the attacker control of the machine or access to sensitive data.

What’s scary is how easy this can be paired with social engineering. Attackers can pose as someone trustworthy—a friend, colleague, or a known brand—and trick victims into opening these deceptive files.

CERT-In’s Alert and Meta’s Response

CERT-In has rated this as high severity and advised all users of the affected versions to update immediately. Meta, WhatsApp’s parent company, has acknowledged the issue and said a patch is already rolled out. There is no evidence of this vulnerability being exploited in the wild yet.

But experts warn the impact of this flaw is big enough to require immediate attention from users and organizations.

What Users Should Do Now

To stay safe, WhatsApp Desktop users should:

• Update Now: Make sure your WhatsApp Desktop is 2.2450.6 or later.

• Don’t Open Unknown Attachments: Don’t open attachments from unknown or suspicious contacts, especially those that look out of context.

• Enable Two-Step Verification: This adds an extra layer of account protection by requiring a PIN to log in.

• Review Linked Devices: Check for any unfamiliar devices linked to your WhatsApp account and remove them.

• Only Use Official Sources: Download WhatsApp updates only from the official website or app stores.

The Bigger Picture: Security Risks of Legacy Frameworks

This incident also highlights larger software development practices from frameworks like Electron, which embeds old Chromium browser code. Even if a platform has encryption and security in place, older frameworks and legacy apps can have unpatched vulnerabilities and be a pathway for modern threats.

Be Aware, Be Current

While WhatsApp is still the leader in its space with over 3.5 billion users, it’s also a target for bad actors. This incident shows how a hacker can get to your messages and why updating and being cautious with messages matters. Users, the fix is easy enough—but the lesson is deeper; trust is not measured by vigilance.

Cybersecurity is not a “set it and forget it” system. Cybersecurity requires constant mental effort and has become necessary for every user since threat actors are evolving faster than technology.

Update your software. Don’t trust unknown files. And no matter what the file looks like, a document.

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