Russian State-Supported Group LAUNDRY BEAR Exploits Zero-Day CVE-2025-66376 in Zimbra Collaboration Suite
Synacor’s Zimbra Collaboration Suite was targeted in a zero-day campaign by the Russian state-backed threat actor known as LAUNDRY BEAR. The stored cross-site scripting flaw in the webmail stylesheet handler allowed attackers to steal past emails simply by having victims view a specially crafted HTML message. No user interaction beyond opening the email was required for JavaScript execution in the browser. On 23 July 2026, sixteen countries including the United States, European nations and Australia issued a joint advisory signed by twenty-seven agencies such as NSA, FBI and CISA. The vulnerability received CVE-2025-66376 and a CVSS v3.1 base score of 7.2, rated High. Analysts assess the campaign focused on intelligence collection against Western government and corporate targets.
Security NEXTJul 27, 2026Translated from Japanese