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Actively exploitedKnown ransomware use

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

Progress WS_FTP Server contains a deserialization of untrusted data vulnerability in the Ad Hoc Transfer module that allows an authenticated attacker to execute remote commands on the underlying operating system.

From the CISA KEV catalogue version 2026.11.06, with Cybergen analysis. Updated 6 Nov 2026.

Our Assessment

Should You Worry?

Patch nowCybergen assessment
  • CISA confirmed exploitation in the wild and added it to the Known Exploited Vulnerabilities catalogue on 5 Oct 2023.
  • CISA lists it as known to be used in ransomware campaigns.
  • Rated Critical severity (CVSS 10.0, scored by Vendor).
  • It has been in the catalogue for 1,128 days. Systems still unpatched now have almost certainly been scanned for it.
The Vulnerability

What It Is

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.

Affected Versions

ProductVersions
Progress Software Corporation WS_FTP Server8.8.0 to before 8.8.2
8.7.0 to before 8.7.4

From the public CVE record, as supplied by the vendor. Always confirm against the vendor advisory.

From Watch to Action

What To Do Now

  1. 1

    Find it

    Search your asset inventory and external attack surface for Progress WS_FTP Server. Include cloud images, appliances and anything a supplier runs for you.

    Attack Surface Management
  2. 2

    Fix it

    Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

    Vulnerability Management
  3. 3

    Hunt for compromise

    If an affected system was reachable before you patched, assume it may have been hit. Check logs, new accounts, web shells and outbound connections from the date of exposure.

    Incident Response
  4. 4

    Prove it is fixed

    Rescan or test the system after patching. Upgrades that fail silently and forgotten secondary instances are common.

    Penetration Testing

Vendor Advisories

Regulation

The Compliance Clock

Cyber EssentialsRated critical, so if it affects devices in your Cyber Essentials scope, the update must be installed within 14 days of the vendor releasing it.NIS2If exploitation causes a significant incident, essential and important entities owe their CSIRT an early warning within 24 hours and a notification within 72 hours.DORAFinancial entities must classify ICT incidents and send an initial notification for a major incident within strict deadlines, with exploited flaws a common cause.US federal (BOD 22-01)Federal civilian agencies had until 26 Oct 2023 to remediate. A sensible benchmark for everyone else.

General guidance, not legal advice. Your obligations depend on your sector, scope and jurisdiction.

Stay Ahead

More Exploited Progress Flaws

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CVE-2026-8037Progress LoadMaster Command Injection VulnerabilityAdded 7 Aug 2026CVE-2024-4885Progress WhatsUp Gold Path Traversal VulnerabilityAdded 3 Mar 2025CVE-2024-1212Progress Kemp LoadMaster OS Command Injection VulnerabilityAdded 18 Nov 2024CVE-2024-6670 · RansomwareProgress WhatsUp Gold SQL Injection VulnerabilityAdded 16 Sep 2024CVE-2024-4358Progress Telerik Report Server Authentication Bypass by Spoofing VulnerabilityAdded 13 Jun 2024CVE-2023-34362 · RansomwareProgress MOVEit Transfer SQL Injection VulnerabilityAdded 2 Jun 2023

All 9 exploited Progress vulnerabilities

Not Sure If You Are Exposed?

Our attack surface and vulnerability teams can check your internet-facing estate for CVE-2023-40044 and every other exploited flaw on the list.

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Evidence

Sources

  1. CISA Known Exploited Vulnerabilities catalogue
  2. NVD: CVE-2023-40044
  3. CVE record: CVE-2023-40044
  4. FIRST EPSS
  5. community.progress.com/s/article/WS-FTP-Server-Critical-Vulnerability-September-2023
  6. progress.com/ws_ftp
  7. theregister.com/2023/10/02/ws_ftp_update/
  8. rapid7.com/blog/post/2023/09/29/etr-critical-vulnerabilities-in-ws_ftp-server/
  9. attackerkb.com/topics/bn32f9sNax/cve-2023-40044
  10. censys.com/cve-2023-40044/
  11. assetnote.io/resources/research/rce-in-progress-ws-ftp-ad-hoc-via-iis-http-modules-cve-2023-40044
  12. packetstormsecurity.com/files/174917/Progress-Software-WS_FTP-Unauthenticated-Remote-Code-Execution.