Learn more about the CageFS symlink bypass vulnerability. Our Server Management Support team is here to help you with your questions and concerns.

About CageFS Symlink Bypass Vulnerability

CageFS is a popular VFS. It is commonly used in web hosting environments in order to improve the security of shared hosting environments. In other words, each user can access only their own virtualized file system. Additionally, this prevents them from accessing other users’ files and directories on the same server.

A symlink acts as a pointer to another file or directory. In some cases, a user can create a symlink that points to a file or directory outside of their virtualized file system. Hence, this allows them to access files or directories belonging to other users on the same server, which is a security vulnerability.

Today, we are going to take a look at the CageFS symlink bypass vulnerability. This security flaw allows attackers with limited user privileges to access files and directories not within their own user directories on shared hosting servers that were using CageFS.

By creating symlinks attackers were able to bypass the security restrictions imposed by CageFS and access files belonging to other users on the server. Furthermore, this allows attackers to read or modify sensitive data. In some cases, they can even take control of the server.

The CageFS symlink bypass vulnerability was first noticed by security researchers in 2019. Fortunately, this prompted CloudLinux to patch the vulnerability immediately. Furthermore, our experts recommend ensuring that hosting providers and users are running the latest version of CageFS to avoid potential vulnerabilities.

Here are some tips by our experts to help you mitigate the risks posed by Symlink vulnerabilities:

• Limit user permissions
• Implement access controls
• Keep software and security tools up to date

Furthermore, systems administrators and developers should be aware of the many risks of symlinks. Additionally, they have to take steps to ensure symlinks are not used maliciously.

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Conclusion

In summary, our Support Techs introduced us to the CageFS symlink bypass vulnerability.