Information disclosure in Ruby - CVE-2021-31810

Detailed vulnerability description

The vulnerability allows a remote attacker to gain access to potentially sensitive information.

The vulnerability exists within Net::FTP in Ruby when processing PASV responses. A remote attacker can trick the victim to connect to a malicious FTP server and trick Net::FTP into connecting back to a given IP address and port. This potentially makes curl extract information about services that are otherwise private and not disclosed (e.g., the attacker can conduct port scans and service banner extractions).

How to mitigate CVE-2021-31810

Sources

• https://www.ruby-lang.org/en/news/2021/07/07/trusting-pasv-responses-in-net-ftp/
• https://hackerone.com/reports/1145454
• https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/MWXHK5UUHVSHF7HTHMX6JY3WXDVNIHSL/