For the first time in history, Windows XP and Server 2003's source codes had been leaked online on 25th September 2020. It was first shared on the 4chan website which was only available for about 4 hours. But unfortunately, the leak had already been uploaded to torrents and other file sharing platforms.
This leak includes both Windows XP and Windows Server 2003's source codes, which is almost 42.9 GB. But this isn't the first time for Microsoft. In 2017, almost a 1GB sized source code of Windows 10 was leaked. It's not yet clear if the full source code of the XP has been leaked. One of Microsoft's representative said that
We are investigating the matter
Microsoft stopped giving support for Windows XP in 2014. But some old Windows users still using this operating system. So, we can hope that Microsoft will take action in this matter soon.