CVE-2018-7600: Drupal Core Remote Code Execution Vulnerability

CVE-2018-7600 is a remote code execution vulnerability in Drupal Core. An attacker who can reach a vulnerable site may exploit multiple attack vectors and achieve complete site compromise. CISA notes known ransomware use, so organizations running Drupal should treat this as a high-priority risk and confirm exact impact and fixed releases against the vendor advisory.

Because successful exploitation can hand an attacker full control of the application and the underlying host, defenders need clear inventory, rapid patching, and compensating controls until updates are in place.

How it works

The weakness is classified as CWE-20 (Improper Input Validation). In products of this class, the application fails to adequately validate or sanitize data supplied by a user or external source before that data is processed by sensitive code paths. When such a flaw exists in a web content-management system, an unauthenticated or low-privilege attacker can often craft requests that cause the application to execute attacker-controlled code.

For CVE-2018-7600 the public description states that multiple attack vectors on a Drupal site can be abused, resulting in complete site compromise. Exact request formats, parameters, and preconditions are not repeated here; teams must obtain those details from the official Drupal security advisory. In general terms, once code execution is obtained the attacker can read or alter the database, install persistent backdoors, pivot to the operating system, and stage further actions such as ransomware deployment.

Am I affected? How to find it in your systems

Drupal Core is commonly deployed as the foundation of public-facing websites, intranets, and customer portals, either on bare metal, virtual machines, containers, or platform-as-a-service offerings. Inventory every instance:

• Search configuration-management databases, CMDB records, and web-server document roots for Drupal installations (look for characteristic files such as core modules, the Drupal bootstrap, or composer.json entries that reference drupal/core).
• Query package managers, container image registries, and orchestration manifests for Drupal packages or images.
• Review virtual-host and reverse-proxy configurations that route traffic to PHP applications known to be Drupal.

Compare the installed Drupal Core version and any applied security patches against the versions listed as vulnerable or fixed in the vendor advisory. Because the flaw can be reached through multiple vectors, assume any unpatched site that is network-reachable is at risk regardless of whether additional modules are present.

Telemetry that may indicate exploitation attempts includes anomalous POST or form submissions to Drupal form and AJAX endpoints, unexpected PHP fatal errors or warnings in application logs, sudden creation of new administrative users, unfamiliar files written under the Drupal root or temporary directories, and outbound connections from the web server process to unfamiliar destinations. Correlate these signals with web-application firewall and IDS alerts that reference CVE-2018-7600 or generic Drupal RCE patterns.

How to remediate

The primary remediation is to apply the security updates released by Drupal for this vulnerability, following the vendor’s instructions exactly. CISA’s required action is to apply updates per vendor instructions. After patching:

• Verify the new Core version is running on every instance and that opcode caches and reverse proxies have been cleared so the updated code is served.
• Rotate credentials for Drupal administrative accounts, database users, and any service accounts that the application uses, because a prior compromise could have captured them.
• Review file-system permissions, ensure the web-server user cannot write to code directories, and confirm that only necessary PHP functions and extensions are enabled.
• Re-baseline configuration and integrity-monitoring tools so future unauthorized changes are detected promptly.

Hardening steps that reduce the attack surface for this class of input-validation flaws include keeping Core and contributed modules on supported release lines, disabling unused modules, enforcing strict Content-Security-Policy and input-filtering defaults, and running the application with the least privileges required.

If you can't patch immediately

When immediate patching is not possible, apply layered compensating controls while scheduling the update:

• Network segmentation: place Drupal hosts in a restricted VLAN or security group; allow inbound traffic only from trusted reverse proxies or WAFs and limit outbound traffic to required destinations.
• Virtual patching: deploy WAF or IPS rules that block known exploit patterns for this CVE once the vendor or reputable threat-intelligence sources publish them; tune to minimize false positives.
• Feature reduction: if the advisory identifies particular form or render pipelines as attack vectors, temporarily disable non-essential form APIs, anonymous posting, or other exposed functionality until the patch is applied.
• Heightened monitoring: increase logging verbosity for the web server and Drupal watchdog, forward logs to a SIEM, and alert on the indicators listed earlier; consider short-term file-integrity monitoring on the Drupal root.
• Access restrictions: require VPN or IP allow-listing for administrative paths and consider placing the site in maintenance mode if business impact allows.

These measures reduce but do not eliminate risk; treat them as temporary bridges to full patching.

If your data may have been exposed

Actively exploited remote-code-execution vulnerabilities, especially those with documented ransomware use, frequently lead to data theft, credential harvesting, and follow-on extortion. If you have evidence of compromise or simply cannot rule it out, preserve forensic images, rotate all secrets, and follow your incident-response plan. As an additional check, you can run a free exposure scan of your email addresses against known breach data sets to see whether associated credentials have already appeared in public dumps.