Threat database

## Summary When cache interception is enabled, `@opennextjs/cloudflare` can interpret percent-encoded paths differently during middleware matching and cache lookup. An encoded request may fail to match authorization middleware, then be decoded into the cache key of a protected route. The cached response may consequently be returned without invoking the middleware. `enableCacheInterception` is disabled by default. ## Impact A remote unauthenticated attacker may retrieve cached content from routes intended to be protected by middleware. An application is affected when it: - explicitly enables `enableCacheInterception`; - relies on middleware for access control; and - has a matching cached route. ## Details Middleware matching previously used the encoded request pathname, while cache interception decoded the pathname before selecting a cache entry. For example, consider an application with: - middleware matcher `/admin/:path*`; - middleware returning `401 Authentication required` for `/admin`; - a statically generated, cached `/admin` route; and - cache interception enabled: ```ts export default defineCloudflareConfig({ incrementalCache: staticAssetsIncrementalCache, enableCacheInterception: true, }); ``` An attacker can request: ```http GET /%61dmin ``` The encoded pathname does not match `/admin/:path*`, so the authorization middleware is not invoked. Cache interception then decodes `%61dmin` to `admin` and may return the cached `/admin` response: ```http HTTP/1.1 200 OK x-opennext-cache: HIT Protected content ``` Malformed paths exposed an additional inconsistency. For example: ```http GET /%61dmin/%ZZ ``` The previous implementation decoded each segment independently. It decoded `%61dmin` to `admin` but retained the malformed `%ZZ` segment, allowing cache lookup to continue using a partially decoded pathname. ## Patches The fix aligns encoded-path handling across middleware matching and cache lookup, and rejects malformed paths instead of partially decoding them. See the upstream fixes in [opennextjs-aws#1199](https://github.com/opennextjs/opennextjs-aws/pull/1199) and [opennextjs-aws#1200](https://github.com/opennextjs/opennextjs-aws/pull/1200). Users should upgrade to `@opennextjs/cloudflare@1.20.2` or later. ## Workarounds If upgrading is not immediately possible for an application: 1. Disable cache interception by removing `enableCacheInterception: true`. 2. Enforce authorization inside protected route handlers rather than relying exclusively on middleware. 3. Reject encoded paths for protected routes at a trusted proxy before they reach the Worker. Adding individual encoded matcher variants is not a complete workaround because pathnames can have multiple equivalent encodings.

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.