Label Studio: Server-side request forgery (CVE-2026-121561)

CVE-2026-121561 affects Label Studio (< 1.23.2) and label-studio-sdk (< 2.1.2). The vulnerability allows an authenticated attacker to perform server-side request forgery (SSRF). By importing tasks with a crafted 'data.image' field, an attacker can coerce the Label Studio server into making unauthorized requests to internal network services. Exporting these tasks via YOLO or COCO formats allows the attacker to retrieve internal service responses, potentially leading to the theft of organization owner API tokens through Host header manipulation.

Attack Chain

1. Attacker authenticates to the Label Studio platform.
2. Attacker submits a task containing a 'data.image' URL pointing to a targeted internal service.
3. Label Studio server processes the image metadata from the task.
4. Attacker initiates an export request using the YOLO or COCO format.
5. The server performs an SSRF request to the internal URL provided in the task metadata.
6. Attacker retrieves the exported file, which includes the response body from the internal service or captured API tokens.

Recommendation

• Upgrade Label Studio to version 1.23.2 or later immediately.
• Upgrade label-studio-sdk to version 2.1.2 or later.
• Audit outbound network egress from Label Studio servers to limit access to sensitive internal infrastructure.