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CVE-2026-56682: CVE-2026-56682: Rate Limiter Lockout Bypass via Header Spoofing in 9Router

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CVE-2026-56682: Rate Limiter Lockout Bypass via Header Spoofing in 9Router

Vulnerability ID: CVE-2026-56682
CVSS Score: 5.3
Published: 2026-09-22

A rate limiting bypass vulnerability in 9Router versions before 0.5.6 allows unauthenticated remote attackers to circumvent the login progressive lockout mechanism. By manipulating the client-supplied X-9r-Real-Ip HTTP header, an attacker can rotate the tracking IP address, enabling unthrottled brute-force password guessing against the administrative interface.

TL;DR

A login lockout bypass in 9Router < 0.5.6 allows remote attackers to conduct unthrottled brute-force attacks against administrative credentials by spoofing the X-9r-Real-Ip HTTP header.

⚠️ Exploit Status: POC

Technical Details

  • CWE ID: CWE-307 / CWE-807
  • Attack Vector: Network (Remote)
  • CVSS Score: 5.3 (Medium)
  • Exploit Status: Proof-of-Concept
  • KEV Status: Not Listed
  • Ransomware Use: No

Affected Systems

  • 9Router versions < 0.5.6
  • 9Router: < 0.5.6 (Fixed in: 0.5.6)

Code Analysis

Commit: efd20be

Implement Loopback Proxy Trust Model to prevent X-9r-Real-Ip header spoofing

Mitigation Strategies

  • Upgrade 9Router to version 0.5.6 or later
  • Configure Next.js to bind exclusively to local loopback interface
  • Strip proxy headers at the perimeter/upstream reverse proxy

Remediation Steps:

  1. Step 1: Pull the latest Docker image or source code for 9Router v0.5.6 or higher.
  2. Step 2: Update configuration files to bind the internal Next.js server to 127.0.0.1 instead of 0.0.0.0.
  3. Step 3: If utilizing a reverse proxy such as Nginx, configure the configuration blocks to strip 'X-9r-Real-Ip' and 'X-Forwarded-For' headers supplied by untrusted clients.
  4. Step 4: Restart the 9Router service and verify rate limiter enforcement by executing consecutive failed authentication requests using different headers.

References

Read the full report for CVE-2026-56682 on our website for more details including interactive diagrams and full exploit analysis.

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