Drupal PHP Templating Engine Cross-Site Scripting Vulnerability [CVE-2019-10909]

CVE Number – CVE-2019-10909

A vulnerability in Drupal could allow an authenticated, remote attacker to conduct a cross-site scripting (XSS) attack against a targeted system.

The vulnerability exists because the affected software does not escape validation messages when the form theme of the PHP templating engine is used. An attacker could exploit this vulnerability by uploading validation messages that submit malicious input to the targeted system. A successful exploit could allow the attacker to conduct an XSS attack, which the attacker could use to execute arbitrary script code or access sensitive information. 

Proof-of-concept (PoC) code that demonstrates an exploit of this vulnerability is publicly available. 

Drupal has confirmed the vulnerability and released software updates.


  • To exploit this vulnerability, the attacker must have user-level access to the targeted system. This access requirement could reduce the likelihood of a successful exploit.


  • Administrators are advised to apply the appropriate updates.

    Administrators are advised to allow only trusted users to have network access.

    Administrators are advised to run both firewall and antivirus applications to minimize the potential of inbound and outbound threats.

    Administrators may consider using IP-based access control lists (ACLs) to allow only trusted systems to access the affected systems.

    Administrators can help protect affected systems from external attacks by using a solid firewall strategy.

    Administrators are advised to monitor affected systems.

Vendor Announcements

  • Drupal has released a security advisory at the following link: sa-core-2019-005

Fixed Software

  • Drupal has released software updates at the following link: Drupal 8.6.15 and 8.5.15

Jason Davies

UK based technology professional, with an interest in computer security and telecoms.

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