Description

Webstudio through 0.296.0 contains an unauthenticated server-side request forgery vulnerability in the /cgi/image, /cgi/video, and /cgi/asset proxy routes when RESIZE_ORIGIN environment variable is unset. Attackers can supply arbitrary URLs to these endpoints to read cloud instance metadata, access internal services, and perform network reconnaissance on the instance infrastructure.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "8.6",
  "pubDate": "2026-09-05T10:16:43.157Z",
  "pubdate": "2026-09-05T10:16:43.157Z",
  "executiveSummary": "Webstudio versions through 0.296.0 are susceptible to an unauthenticated Server-Side Request Forgery (SSRF) vulnerability. This flaw exists within the /cgi/image, /cgi/video, and /cgi/asset proxy routes, specifically when the RESIZE_ORIGIN environment variable is not explicitly configured.\nThe vulnerability allows remote, unauthenticated attackers to force the Webstudio server to initiate unauthorized HTTP requests to arbitrary destinations. By supplying crafted URLs to the affected endpoints, an attacker can pivot from the public internet into the internal network environment.\nThe primary impact of this vulnerability includes unauthorized access to sensitive cloud instance metadata services (e.g., IMDS), interaction with internal-only microservices or APIs, and network reconnaissance of the host infrastructure. This poses a significant risk to the confidentiality and integrity of the hosting environment, as it could facilitate credential theft or unauthorized service interaction. No authentication is required to leverage this vulnerability, making it a critical exposure for deployments relying on default configurations where the RESIZE_ORIGIN variable remains unset.",
  "technicalDetails": "The vulnerability originates from improper input validation and restricted resource access control within the Webstudio proxy middleware. Specifically, the endpoints /cgi/image, /cgi/video, and /cgi/asset are designed to fetch and process media assets from external sources. When the RESIZE_ORIGIN environment variable is left unset, the application fails to enforce a whitelist of permitted origins or validate the destination URL provided by the user.\nThe attack flow begins when an attacker sends a malicious HTTP request to one of the vulnerable /cgi/ routes. The input parameter, intended to specify the source of an image or asset, is instead populated with a target URL internal to the server's network segment or a cloud provider's metadata service (such as 169.254.169.254 for AWS or equivalent endpoints for GCP/Azure).\nBecause the server process executes the request to the supplied URL without sufficient sanitization or protocol restriction, the Webstudio instance acts as an open proxy. The application retrieves the response from the internal target and may return the content to the requester, effectively bypassing firewalls or Network Security Groups (NSGs) that would otherwise protect these internal resources from public access.\nTechnical exploitation steps include: 1. Identification of the target Webstudio instance through reconnaissance. 2. Crafting a GET request targeting the /cgi/image endpoint. 3. Setting the proxy/origin parameter to an internal target, such as http://169.254.169.254/latest/meta-data/iam/security-credentials/ for exfiltrating temporary security tokens. 4. Observing the response from the server to extract sensitive metadata, internal configuration details, or service headers.\nThis vulnerability is present in all Webstudio versions up to and including 0.296.0. The lack of network-level segmentation or application-layer URL validation allows an attacker to perform successful post-exploitation reconnaissance. The impact can escalate to full service compromise if cloud metadata tokens are retrieved, potentially granting the attacker the permissions associated with the instance's IAM role."
}