Executive brief
A security flaw in the WhatsApp application for Windows could allow attackers to trick users into running malicious software. By sending a specially crafted file, an attacker can make a dangerous executable program appear as a harmless document (like a PDF or image) within the chat interface. If a user is deceived into opening the file, the malicious code would run on their computer, potentially compromising their system.
Technical details
An attachment spoofing vulnerability exists in WhatsApp for Windows due to improper neutralization of NUL bytes (CWE-158) in filenames. By embedding NUL bytes in a file's name, an attacker can cause the WhatsApp UI to display a benign file extension while the underlying operating system executes the file based on its true extension (e.g., .exe). This requires user interaction to open the received attachment. The vulnerability is addressed in version 2.3000.1032164386.258709 and later.
Affected products
- Meta WhatsApp for Windows prior to v2.3000.1032164386.258709
Timeline
- 2026-05-01: disclosed
- 2026-05-01: advisory