CVE-2017-6927

Drupal 8.4.x versions before 8.4.5 and Drupal 7.x versions before 7.57 has a Drupal.checkPlain() JavaScript function which is used to escape potentially dangerous text before outputting it to HTML (as JavaScript output does not typically go through Twig autoescaping). This function does not correctly handle all methods of injecting malicious HTML, leading to a cross-site scripting vulnerability under certain circumstances. The PHP functions which Drupal provides for HTML escaping are not affected.

Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.

CVE-2017-6927 has a CVSS score of 6.1 (Medium). The vector is network-reachable, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (8.4.5, 7.57); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2017-6927? CVE-2017-6927 is a medium-severity cross-site scripting (XSS) vulnerability in drupal/core (composer), affecting versions >= 8.4.0, < 8.4.5. It is fixed in 8.4.5, 7.57. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
2. How severe is CVE-2017-6927? CVE-2017-6927 has a CVSS score of 6.1 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which packages are affected by CVE-2017-6927?
   • drupal/core (composer) (versions >= 8.4.0, < 8.4.5)
   • drupal/drupal (composer) (versions >= 8.4.0, < 8.4.5)
4. Is there a fix for CVE-2017-6927? Yes. CVE-2017-6927 is fixed in 8.4.5, 7.57. Upgrade to this version or later.
5. Is CVE-2017-6927 exploitable, and should I be worried? Whether CVE-2017-6927 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2017-6927 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2017-6927?
   • Upgrade drupal/core to 8.4.5 or later
   • Upgrade drupal/core to 7.57 or later
   • Upgrade drupal/drupal to 8.4.5 or later
   • Upgrade drupal/drupal to 7.57 or later