Description
Fclairamb ftpserverlib through 0.32.4 contains a cleartext transmission vulnerability because TransferOpen checks only the transferTLS flag set by PROT, not whether the prepared data connection uses TLS. When a client sends PROT P after PASV or PORT, file contents and directory listings cross the network unencrypted, even with mandatory encryption, letting on-path attackers read or modify them.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| fclairamb | ftpserverlib | ≤ 0.32.4 | — |
| Syncplify | Syncplify Server! | ≤ 8.8.0 | — |
References
- https://github.com/fclairamb/ftpserverlib/pull/685 patch issue-tracking
- https://github.com/fclairamb/ftpserverlib/blob/v0.32.4/handle_misc.go#L29-L31 technical-description
- https://github.com/fclairamb/ftpserverlib/blob/v0.32.4/client_handler.go#L720 technical-description
- VulnCheck Advisory: Fclairamb ftpserverlib through 0.32.4 Cleartext FTPES Data Transfer via PROT P third-party-advisory