Russian cyber campaign infected victims just by viewing an email

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Proofpoint reports Russian TA488 exploited Zimbra zero‑day CVE‑2025‑66376 in espionage campaigns

“Half‑click exploit” let attackers compromise systems when victims merely viewed malicious emails

Targets included NATO, Ukrainian government, and defense entities; group vanished after Feb 2026 exposure

Russian state-sponsored cybercriminals have been abusing a zero-day vulnerability in the Zimbra email and collaboration platform to conduct espionage against western targets - primarily military and government agencies, experts have warned.

Cybersecurity researchers Proofpoint claim the campaign has been ongoing for at least a year, possibly longer, describing it as a “half-click exploit”, because the victims don’t even need to do anything specific in order to get infected.

Usually, when an attack is done via email, the victim is required to at least download a file or click a link. In this case, a cross-site scripting (XSS) vulnerability in the Zimbra web-based email service allowed the Russians to infiltrate the computers as soon as the victim views the email, nothing more.

Targeting NATO and Ukraine

The vulnerability in question is now tracked as CVE-2025-66376. It was assigned a severity score of 7.2/10 (high), and was patched in November 2025. However, the threat actors have been leveraging it long before Zimbra patched it up.

Proofpoint says numerous groups were observed, throughout the years, abusing this flaw. This time around, though, the group in question is tracked as TA488, also known as Laundry Bear or Void Blizzard.

“After successful exploitation, TA488 established persistent access to the systems and exfiltrated emails from the targeted users,” Proofpoint’s report reads. Besides emails, the crooks hunted for passwords, email directories, two-factor authentication tokens, and more. The group has been “consistently” targeting NATO and Ukrainian government organizations, alongside entities in the defense industrial base,

The group seems to be defunct now, since the researchers could not find any activity post February 2026. At that time, security researchers Seqrite disclosed a detailed breakdown of the group’s infrastructure and modus operandi, resulting in TA488 burning down months-old setups and vanishing.