CVE-2026-116844

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.

References

• https://github.com/fclairamb/ftpserverlib/blob/v0.32.4/client_handler.go#L720
• https://github.com/fclairamb/ftpserverlib/blob/v0.32.4/handle_misc.go#L29-L31
• https://github.com/fclairamb/ftpserverlib/pull/685
• https://www.vulncheck.com/advisories/fclairamb-ftpserverlib-through-0.32.4-cleartext-ftpes-data-transfer-via-prot-p