CVE-2023-40044 | WS_FTP Server Ad Hoc Transfer Module .NET Deserialization Vulnerability

Exp

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.

Published: 2023-09-27 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2023-40044 is rated Critical Active Threat (100/100): CVSS Critical severity, with high exploitation likelihood (EPSS 90.15%, 100th percentile). CISA KEV confirms active exploitation (added 2023-10-05) affecting Progress / WS_FTP Server. a weakness (CWE-502) Unauthenticated remote administrative access may be possible. The CISA remediation deadline has passed—treat as an emergency patch priority.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

CISA KEV Record for CVE-2023-40044

Name: Progress WS_FTP Server Deserialization of Untrusted Data Vulnerability · CISA KEV detail

Exploit added: 2023-10-05

Action due: 2023-10-26

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

Public exploit references (Exploit-DB) for CVE-2023-40044

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2023-40044

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-23 90.04% 90.15% +0.11%
2 2026-06-15 94.44% 90.04% -4.39%
3 2025-11-21 — 94.44% —

Full EPSS history (46 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2023-40044

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
10.0 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 6.0 [email protected]
8.8 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.8 5.9 [email protected]

Weakness enumeration for CVE-2023-40044

Affected software / configurations for CVE-2023-40044

Vendor Product Version Raw CPE
progress ws_ftp_server < 8.7.4 cpe:2.3:a:progress:ws_ftp_server:*:*:*:*:*:*:*:*
progress ws_ftp_server >= 8.8, < 8.8.2 cpe:2.3:a:progress:ws_ftp_server:*:*:*:*:*:*:*:*

References for CVE-2023-40044

URL Tags
http://packetstormsecurity.com/files/174917/Progress-Software-WS_FTP-Unauthenticated-Remote-Code-Execution.html Exploit Third Party Advisory VDB Entry
https://attackerkb.com/topics/bn32f9sNax/cve-2023-40044 Third Party Advisory
https://censys.com/cve-2023-40044/ Third Party Advisory
https://community.progress.com/s/article/WS-FTP-Server-Critical-Vulnerability-September-2023 Vendor Advisory
https://www.assetnote.io/resources/research/rce-in-progress-ws-ftp-ad-hoc-via-iis-http-modules-cve-2023-40044 Exploit Third Party Advisory
https://www.progress.com/ws_ftp Product
https://www.rapid7.com/blog/post/2023/09/29/etr-critical-vulnerabilities-in-ws_ftp-server/ Broken Link Third Party Advisory
https://www.theregister.com/2023/10/02/ws_ftp_update/ Press/Media Coverage Third Party Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-40044 US Government Resource
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