A spoofing issue in WhatsApp for Windows prior to version 2.2450.6 displayed attachments according to their MIME type but selected the file opening handler based on the attachment’s filename extension. A maliciously crafted mismatch could have caused the recipient to inadvertently execute arbitrary code rather than view the attachment when manually opening the attachment inside WhatsApp. We have not seen evidence of exploitation in the wild.
Acknowledgements: External Researcher via Meta Bug Bounty submission