WAF emergency rules for Next.js CVE-2025-55173 and CVE-2025-57752
Cloudflare has released emergency WAF rules to block critical Next.js vulnerabilities: CVE-2025-55173 (arbitrary file download) and CVE-2025-57752 (cache poisoning). These rules protect against data exposure and cache manipulation risks affecting production environments.
This week's update
This week, new critical vulnerabilities were disclosed in Next.js’s image optimization functionality, exposing a broad range of production environments to risks of data exposure and cache manipulation.
Key Findings
-
CVE-2025-55173: Arbitrary file download from the server via image optimization.
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CVE-2025-57752: Cache poisoning leading to unauthorized data disclosure.
Impact
Exploitation could expose sensitive files, leak user or backend data, and undermine application trust. Given Next.js’s wide use, immediate patching and cache hardening are strongly advised.
| Ruleset | Rule ID | Legacy Rule ID | Description | Previous Action | New Action | Comments |
|---|---|---|---|---|---|---|
| Cloudflare Managed Ruleset | ...9ff4bfe3 | 100613 | Next.js - Dangerous File Download - CVE:CVE-2025-55173 | N/A | Block | This is a new detection |
| Cloudflare Managed Ruleset | ...69b9ea7d | 100616 | Next.js - Information Disclosure - CVE:CVE-2025-57752 | N/A | Block | This is a new detection |
Source: original entry ↗
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