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Hackers are assailing websites using a prominent WordPress plugin with millions of attempts to exploit a high-severity vulnerability that allows complete takeover, researchers said.

The vulnerability resides in WordPress Automatic, a plugin with more than 38,000 paying customers. Websites running the WordPress content management system use it to incorporate content from other sites. Researchers from security firm Patchstack disclosed last month that WP Automatic versions 3.92.0 and below had a vulnerability with a severity rating of 9.9 out of a possible 10. The plugin developer, ValvePress, silently published a patch, which is available in versions 3.92.1 and beyond.

Researchers have classified the flaw, tracked as CVE-2024-27956, as a SQL injection, a class of vulnerability that stems from a failure by a web application to query backend databases properly. SQL syntax uses apostrophes to indicate the beginning and end of a data string. By entering strings with specially positioned apostrophes into vulnerable website fields, attackers can execute code that performs various sensitive actions, including returning confidential data, giving administrative system privileges, or subverting how the web app works.