CVE-2026-18261 Overview
CVE-2026-18261 is an improper input validation vulnerability [CWE-20] affecting the Drupal Powerful Surveys contributed module. The flaw allows an authenticated attacker with high privileges to compromise the confidentiality and integrity of a Drupal site when a victim user interacts with a crafted request. Drupal published this issue in security advisory SA-CONTRIB-2026-092.
The vulnerability requires network access, high attacker privileges, and user interaction to exploit. Successful exploitation does not directly affect availability, but can expose survey data and modify stored content within the affected Drupal installation.
Critical Impact
Authenticated exploitation of CVE-2026-18261 can lead to disclosure and modification of sensitive survey data managed by the Powerful Surveys module in Drupal.
Affected Products
- Drupal Powerful Surveys contributed module
- Drupal sites with the Powerful Surveys module enabled
- Refer to Drupal Security Advisory SA-CONTRIB-2026-092 for exact affected versions
Discovery Timeline
- 2026-08-25 - CVE-2026-18261 published to NVD
- 2026-08-26 - Last updated in NVD database
Technical Details for CVE-2026-18261
Vulnerability Analysis
The vulnerability is classified as improper input validation [CWE-20]. The Powerful Surveys module accepts input that is not adequately validated before use in downstream processing. An attacker with elevated privileges on the Drupal site can supply malformed or unexpected input to trigger the flaw.
Exploitation requires user interaction, meaning a legitimate user must be induced to perform an action such as clicking a link or submitting a form. The scope remains unchanged, so the impact stays within the security context of the vulnerable Drupal application.
Root Cause
The root cause is insufficient validation of input handled by the Powerful Surveys module. When user-controlled data is processed without proper sanitization or type enforcement, the module can behave in ways not intended by its developers. This creates a path for an authenticated attacker to influence application state or expose data belonging to the survey subsystem.
Attack Vector
The attack vector is network-based. An attacker with high privileges on the Drupal site crafts a request or content that targets the Powerful Surveys module. A separate user must interact with the attacker-supplied payload for the exploit to succeed. Because the attack complexity is high, the attacker must satisfy specific preconditions, such as timing or contextual state, to reliably trigger the flaw.
No public proof-of-concept exploit or exploit database entry is available for CVE-2026-18261 at this time. Technical details of the input validation flaw are documented in the Drupal Security Advisory.
Detection Methods for CVE-2026-18261
Indicators of Compromise
- Unexpected modifications to survey definitions, questions, or response records within Drupal.
- Requests to Powerful Surveys module endpoints containing malformed parameters or unusual payload structures.
- Authenticated sessions from privileged accounts submitting survey-related requests outside normal administrative workflows.
Detection Strategies
- Enable and review Drupal watchdog and dblog entries for errors or warnings originating from the Powerful Surveys module.
- Correlate web server access logs with privileged user activity to identify anomalous POST requests to survey routes.
- Deploy web application firewall rules that inspect input parameters for the Powerful Surveys module and flag unexpected content types or oversized values.
Monitoring Recommendations
- Audit accounts with roles that grant access to the Powerful Surveys module and verify privilege assignments are current.
- Alert on configuration exports or module updates that occur outside of change control windows.
- Monitor for spikes in survey submission volume or error rates that may indicate probing of the vulnerable code path.
How to Mitigate CVE-2026-18261
Immediate Actions Required
- Review Drupal Security Advisory SA-CONTRIB-2026-092 and identify installations running the affected Powerful Surveys module.
- Apply the patched version of the Powerful Surveys module as published by the Drupal maintainers.
- Rotate credentials for administrative and content-editor accounts if suspicious activity is observed.
Patch Information
Drupal published fix guidance in SA-CONTRIB-2026-092. Site operators should update the Powerful Surveys module to the fixed release referenced in the advisory. Verify the module version after upgrade using drush pm:list --type=module --status=enabled or the Drupal administrative extensions page.
Workarounds
- Temporarily disable the Powerful Surveys module on sites that cannot immediately patch, using drush pm:uninstall powerful_surveys or the Extend administration interface.
- Restrict access to survey administration routes at the web server or reverse proxy layer to trusted IP ranges.
- Reduce the number of accounts granted the elevated roles required to reach the vulnerable functionality.
# Update the Powerful Surveys module using Composer and clear caches
composer update drupal/powerful_surveys --with-dependencies
drush updatedb -y
drush cache:rebuild
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
