Cloudflare WAF Adds Rules for Next.js Vulnerability
The update enables monitoring for traffic targeting a specific Brotli-encoded flaw within the image optimization endpoint.
Updated on Oct. 26, 2026 in Cybersecurity
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Cloudflare has released two new Web Application Firewall detection rules designed to identify traffic targeting the CVE-2026-111497 Brotli vulnerability. These rules specifically monitor requests using Brotli body encoding that attempt to access the Next.js image optimization endpoint.
Why it matters
This security update provides immediate detection capabilities for a specific, recently identified vulnerability in the Next.js framework. By flagging potentially malicious requests, the update helps organizations secure web infrastructure against exploits targeting Brotli-encoded traffic.
Cloudflare deployed two new detection rules to its Web Application Firewall which currently operate in Log mode by default. These rules inspect incoming HTTP requests for the specific combination of Brotli body encoding declarations and traffic patterns directed at the Next.js image optimization endpoint.
The players
Cloudflare
A global edge-computing and cybersecurity firm that provides content delivery, DDoS protection, and managed WAF services.
Next.js
A React framework maintained by Vercel that includes built-in features for server-side rendering and image optimization.
The details
The Web Application Firewall, or WAF, operates as an edge-based security layer that inspects incoming HTTP traffic before it reaches a server. By identifying requests that utilize Brotli—a data compression algorithm developed by Google—the rules target traffic that masks exploitation attempts against the Next.js image optimization endpoint. The current configuration places these rules in Log mode, which allows administrators to identify and audit potentially malicious traffic without blocking requests by default.
Timeline
October 25, 2026: Cloudflare released the Web Application Firewall updates.
The Tech Race
This update follows the pattern established by the 2021 Log4j vulnerability response protocols for rapid edge-level mitigation of framework-specific threats. It highlights the ongoing arms race between framework maintainers and security providers to patch endpoint vulnerabilities before they are widely exploited.
Developers and administrators using the Next.js image optimization feature should review their Cloudflare security logs to identify potential matches for these new rules. Since the rules are currently in Log mode, no traffic is blocked by default, requiring manual intervention to transition them to active blocking.
The takeaway
Security teams should monitor their dashboards for activity triggered by these rules to gauge their exposure to CVE-2026-111497. Watch for further documentation from Vercel regarding the vulnerability as the industry standard for remediation crystallizes.
Further reading
For broader trends in edge security, see our coverage of Cybersecurity.
Source note: This article includes information reported by IT Security News - cybersecurity, infosecurity news.
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