---
id: CVE-2026-116844
title: Fclairamb ftpserverlib through 0.32.4 Cleartext FTPES Data Transfer via PROT P
summary: >-
  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 …
severity: medium
cvss: 4.8
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N'
cvssSource: cna
cwe:
  - CWE-319
vendor: fclairamb
product: ftpserverlib
affected:
  - ftpserverlib <= 0.32.4
  - syncplify_server <= 8.8.0
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-10-27T13:42:20.618045Z'
published: '2026-10-27'
updated: '2026-10-29'
sourceUpdated: '2026-10-29T10:52:21.022Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-116844'
references:
  - url: 'https://github.com/fclairamb/ftpserverlib/pull/685'
  - url: >-
      https://github.com/fclairamb/ftpserverlib/blob/v0.32.4/handle_misc.go#L29-L31
  - url: >-
      https://github.com/fclairamb/ftpserverlib/blob/v0.32.4/client_handler.go#L720
  - url: >-
      https://www.vulncheck.com/advisories/fclairamb-ftpserverlib-through-0.32.4-cleartext-ftpes-data-transfer-via-prot-p
    label: >-
      VulnCheck Advisory: Fclairamb ftpserverlib through 0.32.4 Cleartext FTPES
      Data Transfer via PROT P
tags:
  - cve.org
epss: 0.0009
epssPercentile: 0.00403
ingestedAt: '2026-10-27T16:11:59.444Z'
---

## Overview

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

- `ftpserverlib <= 0.32.4`
- `syncplify_server <= 8.8.0`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.