Affecting next package, versions <2.4.1 || >=3.0.0-beta1 <3.0.0-beta7
next is Minimalistic framework for server-rendered React applications.
Affected versions of the package are vulnerable to Directory Traversal via the
/static request namespaces. An attacker can craft a request that may potentially access sensitive information in the server filesystem.
A Directory traversal attack (also known as path traversal) aims to access files and directories that are stored outside the intended folder. By manipulating variables that reference files with “dot-dot-slash (../)” sequences and its variations or by using absolute file paths, it may be possible to access arbitrary files and directories stored on file system including application source code, configuration and other critical system files.
Directory traversal vulnerabilities can be generally divided into two types:
- Information Disclosure: Allows the attacker to gain information about the folder structure or read the contents of sensitive files on the system.
st is a module for serving static files on web pages, and contains a vulnerability of this type. In our example, we will serve files from the
If an attacker requests the following URL from our server, it will in turn, leak the sensitive private key of the root user.
%2e is the URL encoded version of
- Writing arbitrary files: Allows the attacker to create or replace existing files.
This can be achieved using a specially crafted zip archive, that holds path traversal filenames. So when the filename gets concatenated to the target extraction folder, the final path ends up outside of the target folder. If an executable or a configuration file is overwritten with a file containing malicious code, the problem can turn into an arbitrary code execution issue quite easily.
The following is an example of a zip archive with one benign file and one malicious file. Extracting the malicous file will result in traversing out of the target folder, ending up in
/root/.ssh/ overwriting the
2018-04-15 22:04:29 ..... 19 19 good.txt 2018-04-15 22:04:42 ..... 20 20 ../../../../../../root/.ssh/authorized_keys
next to version 2.4.1 or higher.
Do your applications use this vulnerable package?
- Snyk ID
- 31 May, 2017
- 12 Jun, 2017