• Defiant warned of active exploitation of WooCommerce Wholesale Lead Capture Plugin flaw (CVE‑2026‑27540)
• Critical unauthenticated file‑upload bug lets attackers deploy PHP webshells for site takeover
• Patch released in Feb 2026 (v2.0.3.2); Wordfence blocked 100,000+ attacks, users urged to update and check uploads

A critical vulnerability in a popular WooCommerce plugin is being actively exploited to upload malware and possibly take over entire websites, security experts have warned.

The plugin in question is called Wholesale Lead Capture Plugin for WooCommerce. It adds a dedicated registration and onboarding system for wholesale and B2B customers, letting businesses collect company and other custom information, review applications, assign wholesale user roles, and automate registration and onboarding emails.

It is a premium plugin that costs between $99 and $600 and which, according to the Wordpress store page, has more than 20,000 active installations.

A thousand victims

The plugin was vulnerable to an unauthenticated arbitrary file-upload flaw which, as the name suggests, allows unauthenticated parties to upload arbitrary files, including PHP webshells and executable code that can result in full site takeover. It is tracked as CVE-2026-27540 and carries a severity score of 9.0/10 (critical).

Versions 2.0.3.1 and older were said to be affected. Version 2.0.3.2, released on February 20, was said to have addressed the bug, meaning the patch has been available for almost half a year. However, WordPress security outfit Defiant said its Wordfence web application firewall blocked more than 100,000 attacks, and Wordfence added that it observed two attack spikes - one between June 4 and 17, and another one between July 1 and August 30.

In these incidents, the attackers were mostly uploading reconnaissance webshells, possibly mapping out the landscape before deploying more serious malware.

“The uploaded shell.php is a PHP webshell that reports host details and provides a browser-based upload form for writing additional malicious files to the site,” the researchers said.

If you are running the plugin, it is advised you update it to the newest version as soon as possible, and check upload directories for unexpected, or recently created, PHP files.

Via BleepingComputer

• Elastic Security Labs uncovered REF9334, a Brazilian banking malware campaign active since May 2025
• Malware “Kremlin” deploys fake docs and malicious Chrome/Edge extensions to steal banking data
• 1,515 infections found, 98% in Brazil

Security researchers from Elastic Security Labs have discovered a new Brazilian banking malware campaign that uses browser extensions to compromise users and steal sensitive information.

In an in-depth report published earlier this week, the researchers said the campaign has been active since at least May 2025. Dubbed REF9334, the campaign uses fake banking, invoice, and business documents, to trick victims into installing malware which, in turn, deploys a malicious extension in Chrome and Edge browsers.

The researchers named the malware “Kremlin”, and say it can steal browser credentials, cookies, session information, monitor browser activity, grab screenshots, and steal information from websites that the victims visit. But the goal of the campaign is primarily to target Brazilian bank users.

A thousand victims

The malware really makes an effort to hide and persist in the target environment. For example, it first checks to see if it’s in a sandbox and if so - it simply won’t run. If instead it determines that it’s running on a real user’s computer, it will deploy an extension with the name “AVSync System Inc.” in an attempt to trick the victim into thinking they have an antivirus addon running in the browser.

It also doesn’t use a fixed C2 server, but rather stores the information on the Ethereum blockchain, since it’s a lot harder to disrupt the communication between the operators and the infected machines that way.

During their investigation, Elastic researchers were able to take control of a domain that the malware used and discovered that it had infected 1,515 systems. Almost all of them (98%) were located in Brazil. They were also able to register the network canary domain and point it to their webhost, which resulted in the loader assuming it was in a sandbox. This also meant “the infections have not moved past the initial access”, Elastic explained.

The full list of indicators of compromise can be found on this link.

Via The Hacker News