What’s Vulnerable › Vulnerabilities

CVE-2026-116844: Fclairamb ftpserverlib through 0.32.4 Cleartext FTPES Data Transfer via PROT P

• Severity: medium (CVSS 4.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-27 · updated 2026-10-29
• Weakness: CWE-319

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

• fclairamb ftpserverlib: through 0.32.4
• Syncplify, Inc. Syncplify Server!: through 8.8.0

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

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