CVE-2025-6087: OpenNext for Cloudflare (opennextjs-cloudflare) has a SSRF vulnerability via /_next/image endpoint
7.8
Basic Information
JavaScriptTechnical Details
| Package Name | Ecosystem | Vulnerable Versions | First Patched Version |
|---|---|---|---|
| @opennextjs/cloudflare | npm | < 1.3.0 | 1.3.0 |
Vulnerability Intelligence
Miggo AI
Miggo AIRoot Cause Analysis
The vulnerability (CVE-2025-6087) was an SSRF issue in the @opennextjs/cloudflare package, specifically affecting how the /_next/image endpoint handled external image URLs.
The analysis of the provided commit patch (36119c0f490c95b3d4f6e826d745b728c80625ab) reveals that the root cause was an uncontrolled call to the native fetch API within the main request handler of the Cloudflare worker (packages/cloudflare/src/cli/templates/worker.ts).
Before the patch, when the /_next/image?url=<external_url> endpoint was accessed, the fetch method in worker.ts would directly take the external_url and execute fetch(external_url, ...). This allowed an attacker to make the server request arbitrary URLs, leading to SSRF. The server would then proxy the content from the attacker-controlled URL under the victim site's domain.
The patch addressed this by:
- Introducing a new function
fetchImageinpackages/cloudflare/src/cli/templates/init.ts. - This
fetchImagefunction now includes logic to validate the remote URL against a list ofremotePatterns(configured via Next.js image configuration and passed during the build process bypackages/cloudflare/src/cli/build/open-next/compile-init.ts). - The main
fetchhandler inworker.tswas modified to call this newfetchImagefunction instead of directly fetching the URL.
The vulnerable function is therefore the original fetch method in packages/cloudflare/src/cli/templates/worker.ts because it contained the logic that directly processed the user-supplied URL without adequate validation, making the fetch(imageUrl, ...) call the SSRF sink. The other modified files and new functions (fetchImage, matchRemotePattern, compileInit) are part of the mitigation, either by providing the validation logic or the configuration for it.