Security Experts:

Joomla Patches Zero-Day Exploited in the Wild

Joomla released updates and hotfixes on Monday to patch a critical remote code execution vulnerability that has been exploited in the wild.

According to the developers of the popular content management system (CMS), the flaw, caused by the lack of proper filtering when saving browser session values into the database, affects Joomla 1.5.0 through 3.4.5. The security hole has been patched with the release of Joomla 3.4.6 and hotfixes for versions 2.5 and 1.5, both of which have reached end of life (EOL).

Web security company Sucuri reported seeing attacks exploiting this vulnerability starting with December 12, two days before Joomla released patches.

“The attackers are doing an object injection via the HTTP user agent that leads to a full remote command execution,” explained Daniel Cid, founder and CTO of Sucuri.

On December 12 and 13, the security firm spotted hundreds of exploitation attempts coming from three IP addresses:, and

“Today (Dec 14th), the wave of attacks is even bigger, with basically every site and honeypot we have being attacked. That means that probably every other Joomla site out there is being targeted as well,” Cid reported.

The security firm advises Joomla users to check their logs for requests coming from the aforementioned IP addresses. Users can determine if their websites have been compromised by searching the logs for “JDatabaseDriverMysqli” or “O:” in the User Agent.

Joomla is often targeted by malicious actors. In October, cybercriminals started exploiting a SQL injection vulnerability just hours after its details were disclosed. At the time, Sucuri detected attack attempts against all the websites on its network, many of which came from the Tor anonymity network.

Related Reading: Security Flaws Patched in Joomla, Drupal

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Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.