CVE-2026-30242 is a Server-Side Request Forgery (SSRF) vulnerability classified under CWE-918, affecting the open-source project management tool Plane before version 1.2.3. The vulnerability stems from inadequate validation of webhook URLs in the file plane/app/serializers/webhook.py, where the validation logic only checks if the IP address is loopback (127.0.0.1 or ::1). This insufficient check allows an attacker with workspace ADMIN privileges to register webhook URLs that point to private or internal network IP addresses such as those in the ranges 10.x.x.x, 172.16.x.x, 192.168.x.x, and the link-local address 169.254.169.254. When webhook events are fired, the Plane server performs HTTP requests to these attacker-controlled internal addresses and stores the full HTTP response. This behavior enables the attacker to perform SSRF attacks with full response read-back, potentially exposing sensitive internal services, metadata endpoints, or other protected resources within the internal network. The vulnerability does not require user interaction but does require authenticated ADMIN privileges, limiting the attack surface to insiders or compromised admin accounts. The issue was publicly disclosed and patched in Plane version 1.2.3. The CVSS v3.1 base score is 8.5, indicating a high severity due to the ease of network-level exploitation and the potential for significant confidentiality breaches. No known exploits in the wild have been reported as of the publication date. The vulnerability highlights the risks of insufficient URL validation in webhook implementations and the importance of restricting internal network access from externally facing services.

The primary impact of CVE-2026-30242 is the potential exposure of sensitive internal network resources and data due to SSRF attacks. Attackers with ADMIN privileges can leverage this vulnerability to access internal IP ranges that are typically protected from external access, including private subnets and cloud metadata services (e.g., 169.254.169.254). This can lead to disclosure of sensitive configuration data, credentials, or other internal services that could facilitate further lateral movement or privilege escalation within an organization. While the vulnerability does not directly allow code execution or denial of service, the confidentiality impact is high. Organizations using vulnerable versions of Plane risk data leakage and compromise of internal infrastructure confidentiality. The requirement for ADMIN privileges limits exploitation to insiders or attackers who have already compromised an admin account, but the risk remains significant in environments where admin credentials are shared or weakly protected. The vulnerability could also be leveraged in targeted attacks against organizations using Plane for project management, potentially exposing sensitive project or operational data.

To mitigate CVE-2026-30242, organizations should immediately upgrade Plane to version 1.2.3 or later, where the webhook URL validation has been properly fixed to prevent SSRF to internal IP ranges. Until upgrading is possible, administrators should audit existing webhook configurations to identify and remove any webhooks pointing to internal or private IP addresses. Implement network-level controls such as firewall rules or egress filtering to block outbound HTTP requests from the Plane server to internal IP ranges, preventing SSRF exploitation even if webhook URLs are misconfigured. Additionally, restrict workspace ADMIN privileges to trusted users only and enforce strong authentication and access controls to reduce the risk of credential compromise. Monitoring and alerting on unusual outbound HTTP requests from the Plane server can help detect attempted SSRF exploitation. Finally, review and harden webhook handling code and validation logic in custom integrations to ensure robust protection against SSRF and similar injection attacks.