WhatsApp Windows Users at Risk: File Extension Flaw Enables Stealth Malware Attacks

WhatsApp for Windows contains a dangerous security gap that enables attackers to carry out harmful code. Through manipulated attachments, harmless images can be sent that the system can compromise.

Critical security gap in WhatsApp discovered

Meta has disclosed a serious vulnerability in the Windows version of its popular messaging app WhatsApp. The as CVE 2025-30401 Catalogized weakness enables attackers to carry out harmful code on Windows PCs. All WhatsApp versions for Windows before version 2.2450.6 are affected. Users should immediately update the latest version to protect themselves.

The problem lies in the way whatsapp deals with file attachments. The application indicates attachments based on your MIME type (multipurpose Internet Mail Extensions), but selects the file opening handler based on the actual file extension. This discrepancy can take advantage of attackers for their purposes.

This is how the attack works

An attacker could send a .exe file, for example, but what WhatsApp shows as a harmless JPEG image. If the recipient opens the appendix manually within the app, the hidden malice code is executed instead of the expected image display. This type of spoofing attack is particularly dangerous, since many users regularly exchange pictures and files in WhatsApp groups and there is a certain basic confidence.

According to the security warning (via Bleeping computer) was discovered by an external researcher and reported via the Meta Bug Bounty program. The exploitation of this gap could lead to the execution of any codes on the target system, which would enable attackers far -reaching control over the affected computer.

The current security gap is based on a classic discrepancy between the file type detection and file treatment. MIME types were originally developed for email attachments to identify the content of a file regardless of their ending. In this case, WhatsApp uses the MIME type for the preview, but relies on the file extension when executing – a dangerous combination that attackers can take advantage of. Security experts advise WhatsApp users to exercise extreme caution when opening attachments – even if they come from known contacts.

Ideally, you should treat WhatsApp with the same caution as emails and never unexpected files, especially not from new contacts.