VShell

A pre-authentication SQL injection vulnerability in Roundcube Webmail, tracked as CVE-2026-48842, is being actively exploited in the wild. The flaw exists in the virtuser_query plugin of versions 1.6.x before 1.6.16 and 1.7.x before 1.7.1, allowing unauthenticated attackers to inject arbitrary SQL and potentially access mail account credentials and stored messages. The Canadian Centre for Cyber Security and SentinelOne have confirmed active exploitation, though specific threat actor details remain limited. Patches were released in May 2026, but over 500,000 Roundcube instances remain internet-exposed, with at least 10 identified as vulnerable as of late September 2026.

A cybercrime group operating under the name WP-SHELLSTORM left a server exposed for 22 days, revealing their infrastructure and tools used to backdoor over 5,700 WordPress and Joomla sites. The group exploited known vulnerabilities in plugins like Breeze (CVE-2026-3844) and Joomla JCE (CVE-2026-48907), deploying webshells such as down.php and using the SNOWLIGHT dropper to install the VShell backdoor. The exposed server contained logs, exploit scripts, and target lists of over 1.4 million domains, highlighting a financially motivated, Chinese-speaking crew with poor operational security.

A China-linked threat cluster tracked as UNK_MassTraction has been exploiting vulnerabilities in Roundcube webmail servers at academic institutions in the U.S. and Canada since May 2026. The attackers target physics and engineering departments, deploying malware to steal credentials and establish persistent access. Exploitation involves CVE-2024-42009 and CVE-2025-49113 to deploy backdoors such as IceCube, SquareShell, and VShell. Proofpoint attributes the activity to a likely China-aligned espionage group based on infrastructure overlap and linguistic artifacts, though confidence is moderate.