CVE-2026-82241 SSRF Vulnerability in Budibase REST Datasource Preview

CVE-2026-82241 identifies an SSRF vulnerability within the Budibase backend-core library, which is a component of the Budibase server. The vulnerability stems from an incomplete blacklist configuration that fails to account for the CGNAT address range 100.64.0.0/10. When an administrator has not manually configured a custom BLACKLIST_IPS list, the application defaults to an inadequate set of restricted addresses.

An authenticated attacker with 'Builder' permissions can exploit this by interacting with the POST /api/queries/preview endpoint. By submitting a crafted REST datasource query preview request, the attacker can force the Budibase server to perform an HTTP(S) request to arbitrary services within the 100.64.0.0/10 range. Because the preview functionality returns the response content to the user, this allows for sensitive data exfiltration or internal network reconnaissance. There is currently no vendor patch; the remediation requires manual configuration of the blacklist.

Attack Chain

1. Attacker gains access to a Budibase instance with 'Builder' level permissions.
2. Attacker navigates to the REST datasource management interface to configure a new query.
3. Attacker identifies a target service residing within the internal 100.64.0.0/10 CGNAT range.
4. Attacker crafts a HTTP POST request to the /api/queries/preview endpoint with the target URL in the query body.
5. The Budibase server fails to validate the target URL against the restricted 100.64.0.0/10 range.
6. The backend server initiates an outbound request to the target internal service.
7. The internal service responds to the server request.
8. The Budibase server serializes the internal response and returns the data to the attacker via the UI/preview flow.

Impact

Successful exploitation allows for unauthorized interaction with internal HTTP services that are intended to be protected from public or user-level access. This can lead to the exfiltration of sensitive information, unauthorized modification of internal state, or reconnaissance of the internal network architecture.

Recommendation

• Immediately update the Budibase BLACKLIST_IPS environment variable to include the 100.64.0.0/10 range as specified in the advisory for CVE-2026-82241.
• Monitor access logs for POST requests to /api/queries/preview to identify potential abuse of the datasource preview feature by users with 'Builder' permissions.
• Restrict administrative 'Builder' access to only trusted personnel to mitigate the risk of account-based exploitation.