Kiteworks urges customers worldwide to shut servers for six hours over 'imminent' zero-day threat
Kiteworks has told customers worldwide to shut down their servers for a six-hour window on Saturday after receiving intelligence that a cyberattack may be imminent.
Secure file-transfer company Kiteworks has urged customers around the world to shut down their servers for a six-hour window on Saturday after receiving intelligence that a cyberattack may be imminent.
The notice, first reported by German outlet Heise from a customer email, sets the offline window at 02:00–08:00 UTC on Saturday 26 September — 03:00–09:00 in the UK, 04:00–10:00 in central Europe and 22:00 Friday–04:00 Saturday in New York. Servers should be shut down before the window begins, even where they are not directly accessible from the internet.
“We have received credible threat intelligence from law enforcement indicating an attack on Kiteworks systems may be imminent this weekend,” the email said — attributed to CISO Frank Balonis by Computer Weekly and BleepingComputer, but to CEO Jonathan Yaron by Cybernews.
No CVE, patch or technical details have been published. Kiteworks support told Heise the shutdown was a precaution against potential zero-day attacks, but the company has not confirmed that any unknown vulnerability exists or is being exploited. It confirmed the warning to BleepingComputer, stressing it is preventative: “We are not aware of any compromise of Kiteworks systems.”
Kiteworks, formerly Accellion, claims more than 1,500 customers serving over 100 million end users, per its website as reported by Cybernews.
Jake Knott, head of threat intelligence at watchTowr, called the move “highly unusual, and a very bad sign”.
Sources
- Computer Weekly, “Expecting cyber attack, Kiteworks tells users to turn off servers”, 25 Sep 2026 — https://www.computerweekly.com/news/366651301/Expecting-cyber-attack-Kiteworks-tells-users-to-turn-off-servers
- BleepingComputer, “Kiteworks urges 6-hour server shutdown over potential zero-day attacks” — https://www.bleepingcomputer.com/news/security/kiteworks-urges-6-hour-server-shutdown-over-potential-zero-day-attacks/
- Cybernews, “Kiteworks zero-day warning: customers urged to shut down systems” — https://cybernews.com/security/kiteworks-cyberattack-imminent-server-shutdown/
- Heise (German outlet), as cited by Computer Weekly and BleepingComputer
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