The vulnerability exists in the image generation flow of ApostropheCMS’s AI helper module. When a user with editor privileges requests a base64 image that has no stored provider URL, the server resolves the upload path using the Host header supplied in the request. This causes a server‑side request to a host, port, and HTTP origin chosen by the attacker. The attack does not allow arbitrary path traversal or retrieval of stored‑provider images but is sufficient for bounded SSRF. The weakness is a classic Server‑Side Request Forgery (CWE‑918).

Affected products are the @apostrophecms/ai-helper package used by ApostropheCMS, specifically versions 1.0.0‑beta.10 through 1.0.0‑beta.13. Any site that employs that module within this version range and allows editors to generate images is vulnerable. The main product label is ApostropheCMS content management system.

The CVSS score of 4.3 places the vulnerability in the moderate severity range. EPSS data is not available, so the real-world exploitation probability is unknown, and the vulnerability is not listed in CISA’s KEV catalog. The issue requires the attacker to be an authenticated editor, so it is not public‑supply. The attacker can direct the site to send HTTP requests to a target host, exposing potential internal resources. The bounded nature limits the impact but still poses a risk to confidentiality and availability of internal services.