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

100

Patch now

CRITICAL 10.0EXPLOITEDREMOTEUPGRADE

CVE-2023-40044 is a critical-severity flaw (CVSS 10.0) affecting ws ftp server, reported as exploited in the wild. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

In WS_FTP 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 WS_FTP Server operating system.

Why this priority

Critical severity
EPSS top 1%: very likely to be exploited
Exploited in the wild (CISA KEV)
Used in ransomware campaigns
Public exploit reference
CISA SSVC: automatable with total technical impact
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	10.0 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	90.4% (top 1%)
CISA exploited list	Yes, fix due 2023-10-26, used in ransomware
Weakness	CWE-502
Published	2023-09-27
Last modified	2026-06-17

Publisher (CNA): Progress Software Corporation · Vendor: progress

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2023-09-27 15:18 UTCPublished CVE record published
2023-10-05Exploited Added to the CISA Known Exploited Vulnerabilities list
2023-10-26Deadline CISA due date for US federal agencies to patch
2026-06-17 06:15 UTCUpdated Record last modified

progress ws ftp server UPGRADE

Affected: < 8.7.4 · >= 8.8 and < 8.8.2

Fixed in: 8.7.4, 8.8.2

Safe to downgrade to: a release before 8.8

1. Check installed version

apt-cache policy ws-ftp-server || rpm -q ws-ftp-server || ws-ftp-server --version

2. UPGRADE to 8.7.4 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade ws-ftp-server

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade ws-ftp-server

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 8.8 (Debian / Ubuntu)

apt-cache madison ws-ftp-server sudo apt install ws-ftp-server=<VERSION_BEFORE_8.8> sudo apt-mark hold ws-ftp-server

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list ws-ftp-server sudo dnf downgrade ws-ftp-server-<VERSION_BEFORE_8.8> sudo dnf versionlock add ws-ftp-server

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Exact fixes by distribution

Fedora ELN · libmamba · FIXED · 2.10.0-1.eln159 · FEDORA-2026-cc57be9e65 · source

sudo dnf upgrade --advisory=FEDORA-2026-cc57be9e65

Fedora 46 · rubygem-selenium-webdriver · FIXED · 4.34.0-5.fc46 · FEDORA-2026-111c6e6363 · source

sudo dnf upgrade --advisory=FEDORA-2026-111c6e6363

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

GitHub PoC: kenbuckler/WS_FTP-CVE-2023-40044 (1 stars)
Write-up: attackerkb.com/topics/bn32f9sNax/cve-2023-40044
Write-up: www.assetnote.io/resources/research/rce-in-progress-ws-ftp-ad-hoc-via-iis-http-modules-cve
Write-up: www.rapid7.com/blog/post/2023/09/29/etr-critical-vulnerabilities-in-ws_ftp-server/
Metasploit: Progress Software WS_FTP Unauthenticated Remote Code Execution
Nuclei scan template: WS_FTP Server - Insecure Deserialization

Verify at the official source NVD · CVE Program · CISA KEV catalog · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2023-40044?

ws ftp server: upgrade to 8.7.4, 8.8.2. Exact commands for each OS are on this page.

Is CVE-2023-40044 being exploited?

Yes. CVE-2023-40044 is on the CISA Known Exploited Vulnerabilities list, so treat it as patch-now.

What does CVE-2023-40044 affect?

CVE-2023-40044 affects ws ftp server. Severity is critical (CVSS 10.0). In WS_FTP 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 WS_FTP Server operating system.

How urgent is CVE-2023-40044?

Priority 100/100. Critical severity; EPSS top 1%: very likely to be exploited; Exploited in the wild (CISA KEV); Used in ransomware campaigns; Public exploit reference; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action

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References

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