Open-Source Security Intelligence

Know every vulnerability
before it knows you.

DevGuard continuously monitors your dependencies and alerts you when CVEs like this one affect your stack — with real-time threat intelligence built for developers.

Search

GHSA-vrgw-pc9c-qrrc

CriticalCVSS 9.9 / 10
Published Jan 13, 2026·Last modified Feb 3, 2026
Affected Components(0)

No affected components available

Description

Impact

Within Umbraco Forms, configuring a malicious URL on the Webservice data source can result in Remote Code Execution. This affects all Umbraco Forms versions running on .NET Framework (up to and including version 8).

Patches

The affected Umbraco Forms versions are all End-of-Life (EOL) and not supported anymore, hence no patches will be released. Upgrading to any of the currently supported versions (v13, v16 or v17) is recommended.

Workarounds

If none of the configured Forms data sources uses the Webservice type, it can be safely excluded by adding the following code to the application. This will completely remove the option to select/use this data source within the Backoffice and thereby mitigate the vulnerability.

using Umbraco.Core.Composing;
using Umbraco.Forms.Core.Providers;
using Umbraco.Forms.Core.Providers.DatasourceTypes;

internal sealed class RemoveFormsWebserviceDataSourceTypeComposer : IUserComposer
{
    public void Compose(Composition composition)
        => composition.WithCollectionBuilder<DataSourceCollectionBuilder>().Exclude<Webservice>();
}

Any Webservice data source that is configured and still in use should be replaced with a custom implementation instead, before applying the above code. If this is not feasible, the vulnerability can be minimized by revoking the 'Manage Data Sources' from any non-administrator user and/or inheriting from the default Umbraco.Forms.Core.Providers.DatasourceTypes.Webservice class and overriding the ValidateSettings() method to ensure only trusted URLs can be used.

References

When upgrading to a supported version, please take the Forms version specific upgrade notes into account and check the CMS upgrade documentation. Content and schema can also be migrated straight to the latest version using Deploy export/import with migrations.

Implementation details on data sources are not extensively documented, but they follow the general Forms provider model and inherit from Umbraco.Forms.Core.FormDataSource.

A special thanks to Piotr Bazydlo (@chudyPB) of watchTowr for finding and disclosing this vulnerability

Risk Scores
Base Score
9.9

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker needs basic access or low-level privileges. No user interaction is needed for the attacker to exploit this vulnerability. The vulnerability can affect other systems as well, not just the initial system. There is a high impact on the confidentiality of the information. There is a high impact on the integrity of the data. There is a high impact on the availability of the system.

Threat Intelligence
9.1

Active exploitation in the wild has been confirmed. Immediate patching or mitigation is required.

EPSS
N/A

Probability that this vulnerability will be exploited in the wild within the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

Scan your project

Continuously monitor your dependencies and get alerted when vulnerabilities like this one affect your stack.

Checkout DevGuard