SA-CONTRIB-2026-160: Critical severity drupal/webform vulnerability
The Webform module allows site builders to create forms, collect submissions, and configure access to forms and submission data. Site builders may also configure handlers for processing submissions. Remote Post Handlers send webform data to other servers via APIs. The module does not sufficiently filter response values from the Remote Post handler before those values are rendered through handler response tokens. If a site uses Remote Post handler response tokens in rendered output, values returned by a configured remote endpoint could be rendered as HTML, resulting in a cross-site scripting vulnerability. This vulnerability is mitigated by the fact that an attacker must be able to control or influence the response from a configured remote endpoint, and the site must use Remote Post handler response tokens in rendered output.
Credit
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
drupal/webformto a version that resolves this vulnerability.Fixed in 6.2.12Fixed in 6.3.1
Event History
Frequently Asked Questions
Which sites are exposed to this issue?
A site is exposed only if it uses a Remote Post handler and renders that handler's response tokens in output. Sites that do not render Remote Post handler response tokens are not affected by the described attack path.
What must an attacker control to exploit it?
The attacker must be able to control or influence the response returned by a remote endpoint configured in a Remote Post handler. That response must then be rendered through handler response tokens.
What is the practical impact of successful exploitation?
Attacker-influenced response values can be rendered as HTML, resulting in cross-site scripting. The issue is therefore dependent on both the remote endpoint's response being influenceable and the relevant tokens being used in rendered output.
What can be done if patching is not immediately possible?
Avoid rendering Remote Post handler response tokens in output, and review configured remote endpoints to ensure untrusted parties cannot control or influence their responses.