Russian espionage group using novel Zimbra exploit to steal sensitive data from Western countries

Laundry Bear exploited a zero-day vulnerability for five months before it was patched in November 2025, and the group is still actively exploiting vulnerable environments.

A Russian state-sponsored threat group has been stealing sensitive data from governments and commercial organizations since July 2025 via a novel exploit in popular Linux-based enterprise software, U.S. authorities and cyber officials from more than a dozen other countries warned in a joint cybersecurity advisory Thursday.

Laundry Bear’s most recent espionage campaign involves the exploitation of a zero-day vulnerability in Zimbra Collaboration Suite that wasn’t patched until November 2025, five months after attacks were well underway, officials said. 

The exploit just requires a view — no clicks — and allows attackers to steal the previous 90 days’ worth of email, the account’s password, search history, the victim organization’s email directory, two-factor authentication tokens and other newly created passwords.

“The covert and persistent nature of this activity, along with the absence of any known financial extortion, almost certainly indicates this group’s involvement in espionage activities with Russian government backing,” officials wrote in the advisory. 

“Additionally, extensive Ukrainian targeting, prior to use against U.S. and other NATO allies, outlines an increasing trend within Russian cyber threat groups to target Ukrainian users first—both as a priority target and as a testbench for malicious cyber techniques before broader global deployment.”

The state-sponsored espionage group, also known as Void Blizzard, has compromised governments and organizations in the defense, education, energy, law enforcement, media, finance, transportation and technology sectors. 

Laundry Bear’s year-long campaign involving the exploitation of CVE-2025-66376 showcases more technical capabilities, including a custom JavaScript payload it delivers to targeted victims via phishing emails. The threat group could also likely adapt the novel data exfiltration and aggregation capability, dubbed “beehive,” to exploit other vulnerabilities, officials warned.

The defect’s medium-severity rating of 6.1 underscores the challenge defenders regularly confront in prioritizing patching schedules based on measure of severity alone.

The Russian state-supported group, which has been active since at least 2024, is still actively exploiting Zimbra Collaboration Suite instances that remain unpatched, officials said.

Authorities shared Thursday indicators of compromise, mitigation steps and urged organizations to update their vulnerable software.

“This campaign’s targeted victimology and limited exploitation capabilities likely indicate this group manually identifies and targets the victim organizations” by identifying organizations with public-facing infrastructure, officials wrote in the advisory.

Once a target is identified, Laundry Bear also likely compiles email addresses for users to target with the exploit via phishing emails. Officials did not identify specific victims or describe the volume of organizations already compromised.

The joint cybersecurity advisory was issued by the United States, Australia, Canada, New Zealand, the United Kingdom, Czech Republic, Denmark, Estonia, Finland, France, Italy, Moldova, the Netherlands, Poland, Spain and Sweden.

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