Sublime Security observed a 1,216% month-over-month increase in malicious calendar invites in August 2026, with the first half of September surpassing the entire month of August by 1,426%.
The vulnerability or weakness
The attacks leverage the .ics file format, which is a valid calendar data format, to trick users into downloading malicious software or entering credentials on a spoofed sign-in page.
Earlier attacks and coverage
No earlier related attack in our archive yet.
Business impact
This increase poses a significant risk to organizations by potentially leading to data breaches and loss of sensitive information, impacting operations and potentially resulting in financial losses.
Industries affected
All industries are affected, as calendar invites can be sent to any user with a calendar and email account.
Users affected
Not stated in the sources.
Build these skills
Sources
- Quarantined, but still on your calendar: The explosion of invite-based attacks (Help Net Security)
