Label Studio versions through 1.23.0 contain a Server-Side Request Forgery (SSRF) vulnerability due to missing validation of webhook URLs. Authenticated users can craft webhook requests targeting internal services, RFC 1918 private network addresses, and cloud metadata endpoints. This allows attackers to probe and interact with internal infrastructure that would otherwise be inaccessible. Additionally, by enabling payload transmission in outbound webhook requests, attackers can exfiltrate sensitive annotation data to attacker-controlled endpoints. The vulnerability requires authentication but poses significant risk in multi-tenant or shared environments. A fix has been committed and is referenced in the project's GitHub repository. The issue was reported and tracked via GitHub issue #9801 and documented by VulnCheck.
