---
title: "CVE-2023-40044: Progress WS_FTP Server Deserialization of Untrusted Data Vulnerability"
url: https://erroneo.us/security/cve/CVE-2023-40044/
description: "CVE-2023-40044 (Progress WS_FTP Server): Exploited in the wild (CISA KEV). In WSFTP Server versions prior to 8.7.4 and 8.8.2, a pre-authenticated attacker…"
type: vulnerability-record
section: "Security Digest"
date_published: 2023-09-27
date_modified: 2025-10-21
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2023-40044"
kev: true
cvss: 10
epss: 0.90355
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2023-40044: Progress WS_FTP Server Deserialization of Untrusted Data Vulnerability

**Signal:** Exploited: patch now if you run it. CISA has confirmed exploitation in the wild. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Yes, if you run Progress WS_FTP Server. CISA added this CVE to its Known Exploited Vulnerabilities catalog on 2023-10-05, which means there is reliable evidence of exploitation in the wild. US federal agencies must remediate by 2023-10-26 ; treat that as the outer limit, not the target. CISA also lists it as known to be used in ransomware campaigns .
- EPSS 90.4% , percentile 99.8: FIRST’s model estimates a 90.4% chance of exploitation activity in the next 30 days, higher than 99.8% of all scored CVEs (very high). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.

## What it is

In WSFTP Server versions prior to 8.7.4 and 8.8.2, a pre-authenticated attacker could leverage a .NET deserialization vulnerability in the Ad Hoc Transfer module to execute remote commands on the underlying WSFTP Server operating system.

## Affected products (CVE record)

- Progress Software Corporation WS_FTP Server: 8.8.0 < 8.8.2, 8.7.0 < 8.7.4

## Severity

- ProgressSoftware CVSS 3.1: 10 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H`

## Exploitation

- CISA KEV: added 2023-10-05; federal due date 2023-10-26. Known ransomware use: Known.
- CISA required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
- CISA SSVC assessment: exploitation active , automatable yes , technical impact total .
- FIRST EPSS (model of 2026-10-21): 90.35% probability of exploitation activity in the next 30 days; percentile 99.8.

## Sources

- [community.progress.com](https://community.progress.com/s/article/WS-FTP-Server-Critical-Vulnerability-September-2023)
- [CVE.org record CVE-2023-40044](https://www.cve.org/CVERecord?id=CVE-2023-40044)
- [NVD entry CVE-2023-40044](https://nvd.nist.gov/vuln/detail/CVE-2023-40044)
- [CISA Known Exploited Vulnerabilities catalog entry](https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-40044)
- [progress.com](https://www.progress.com/ws_ftp)
- [theregister.com](https://www.theregister.com/2023/10/02/ws_ftp_update/)
- [rapid7.com](https://www.rapid7.com/blog/post/2023/09/29/etr-critical-vulnerabilities-in-ws_ftp-server/)
- [attackerkb.com](https://attackerkb.com/topics/bn32f9sNax/cve-2023-40044)
- [censys.com](https://censys.com/cve-2023-40044/)
- [assetnote.io](https://www.assetnote.io/resources/research/rce-in-progress-ws-ftp-ad-hoc-via-iis-http-modules-cve-2023-40044)
- [packetstormsecurity.com](http://packetstormsecurity.com/files/174917/Progress-Software-WS_FTP-Unauthenticated-Remote-Code-Execution.html)

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Source page: https://erroneo.us/security/cve/CVE-2023-40044/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt