Russian hackers have reportedly stolen emails from users of the Zimbra communication program, impacting the United States and over ten allied nations, including the Czech Republic. The breach did not require victims to open attachments or click on links, making it particularly insidious. Cybersecurity firm Proofpoint identified the attack as exploiting a previously patched vulnerability within Zimbra software. This allowed hackers to compromise systems simply by victims opening an email. The US government has released a security advisory regarding the vulnerability. This incident underscores the continuing threat posed by Russian cyber activity and the importance of promptly patching software vulnerabilities. Further investigation is underway to determine the full scope of the data stolen and the extent of the compromise.