Label Studio through version 1.23.0 allows authenticated users to create webhooks without validating the target URL, giving attackers the ability to send requests to arbitrary local or internal addresses. This flaw can be used to reach RFC 1918 private networks or cloud metadata endpoints, enabling the exfiltration of annotation data when outbound payloads are enabled. The vulnerability exposes confidential data and potentially provides a pivot into internal services, increasing the threat surface for an adversary.

HumanSignal Label Studio versions up to and including 1.23.0 are affected. The flaw is present on all installations that have not applied the later patch version. No specific subversions are listed beyond the cutoff at 1.23.0.

The CVSS score of 8.4 places the issue in the high severity range, reflecting significant impact if exploited. EPSS data is not provided, but the lack of URL validation means the flaw is trivially exploitable by any authenticated user with webhook creation rights. The vulnerability is not currently listed in the CISA KEV catalog, though its potential for internal exploitation makes it a high‑risk concern for environments exposing internal services to webhooks.