What is the CVSS score of CVE-2026-44403?

CVE-2026-44403 has a CVSS 4.0 base score of 8.6 (High). CVSS vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N. EPSS exploitation probability: 0.1%.

Is there a public PoC exploit available for CVE-2026-44403?

Yes, a public proof-of-concept exploit is available for CVE-2026-44403. Prioritise patching immediately. EPSS: 0.1%.

How to fix or mitigate CVE-2026-44403?

Within 24 hours: conduct inventory of all Wing FTP Server 8.1.2 instances and review domain administrator access logs for suspicious activity. Within 7 days: implement network segmentation restricting FTP server access to trusted networks only, enforce privileged access management for all domain administrator accounts, and disable Lua scripting if not operationally required. Within 30 days: migrate to an alternative FTP server with active security updates or deploy comprehensive logging and alerting on Lua execution and session activities to detect exploitation attempts.

Wing FTP Server CVE-2026-44403

EUVD-2026-29848 HIGH

Code Injection (CWE-94)

2026-05-12 VulnCheck

GHSA-ffh5-r5xj-cgmg

RCE Code Injection Wing Ftp Server

8.6

CVSS 4.0 · NVD

View

Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

Access

Obtain domain admin credentials
Delivery

Log into Wing FTP admin interface
Exploit

Inject Lua via mydirectory field
Execution

Session serialized to Lua source
Persist

loadfile() reloads poisoned session
Impact

Execute arbitrary code on server

Vulnerability Assessment

Weakness	CWE CWE-94 OWASP Top 10:2025 A05:2025 - Injection ASVS 5.0 V1 - Encoding and Sanitization Code injection prevention, sandbox exec MITRE ATT&CK 2 techniques across 2 tactics: Execution, Initial Access The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. Sign in to read
Exploitation Conditions	Exploitation requires an authenticated domain administrator account on Wing FTP Server 8.1.2 (CVSS PR:H) and the ability to set the domain admin 'mydirectory' field, whose value is unsafely serialized into Lua source and re-executed via loadfile(). No end-user interaction is needed (UI:N) and the vector is network-reachable (AV:N) through the admin interface. The primary limiting factor is the high privilege prerequisite: only accounts already trusted with domain administration can trigger it, so it functions as an admin-to-server-RCE escalation rather than an unauthenticated compromise; it is therefore not automatable (SSVC Automatable: no) and not suited to opportunistic mass exploitation.
Impact	Signals are largely consistent and point to a real but privilege-gated issue. The CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:H/UI:N, VC:H/VI:H/VA:H) scores 8.6 and reflects network reach and total confidentiality/integrity/availability impact, but critically requires PR:H - a domain administrator account. CISA's SSVC framework aligns: Exploitation 'none' (not observed in the wild), Automatable 'no' (requires authenticated admin context, not mass-scannable), and Technical Impact 'total'. EPSS is very low at 0.09% (25th percentile), and the vulnerability is not in CISA KEV, so despite public exploit code this is not a wormable or opportunistic threat. The honest read: this is a post-authentication privilege-to-code-execution escalation for an already-trusted admin, valuable to an attacker who has phished or otherwise obtained admin credentials, but not a spray-and-pray internet risk. The high CVSS is driven by impact, not by ease of unauthenticated access.
Exploit ScenarioDerived	An attacker who has obtained (or been improperly granted) domain administrator access logs into the Wing FTP admin interface and sets the domain admin 'mydirectory' field to a payload containing a Lua string-closing delimiter followed by malicious Lua. When the server serializes and later reloads the session via loadfile(), the injected Lua runs in the server process, giving arbitrary command execution. A public proof-of-concept is available (Exploit-DB 52589), lowering the skill needed to reproduce it.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).

No patch listed yet 0.1% exploitation probability (EPSS)

Get an e-mail when this CVE is exploited, patched or re-scored. Free account.

Alert me

AnalysisAIv1 – Jul 23, 2026

Authenticated remote code execution in Wing FTP Server 8.1.2 lets a domain administrator inject arbitrary Lua code by abusing the session serialization routine, which writes session values into Lua source without escaping closing delimiters. When the poisoned session is later reloaded through loadfile(), the attacker's Lua executes on the server. Publicly available exploit code exists (Exploit-DB 52589, VulnCheck advisory), but there is no evidence of active exploitation and EPSS is very low (0.09%).

RemediationAI

Upgrade to a fixed Wing FTP Server release once published - no exact patched version number is confirmed in the available data, so consult the vendor version history at https://www.wftpserver.com/serverhistory.htm for the first release after 8.1.2 and the VulnCheck advisory (https://www.vulncheck.com/advisories/wing-ftp-server-authenticated-remote-code-execution-via-session-serialization) for the fixed build before deploying. Until a patched build is applied, reduce exposure by tightly restricting who holds domain administrator accounts and enforcing strong, unique credentials plus MFA on the admin web interface, since exploitation requires admin-level access; additionally, restrict network access to the administration console to trusted management hosts or a VPN so stolen credentials cannot be used remotely, and audit the 'mydirectory' domain admin field and generated session files for anomalous Lua content. These controls limit reachability but do not remove the underlying injection, which only the vendor fix addresses.

Affected VersionsENISA

Wing FTP Server 8.1.2

Affected Packages

euvd wing_ftp_server no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

Wing FTP Server is a commercial multi-protocol (FTP/FTPS/SFTP/HTTP) file transfer server whose administrative and scripting layer is built on an embedded Lua interpreter. Session state is persisted by serializing values directly into a generated Lua source file, then re-materializing that file at runtime with loadfile(). Because the serializer does not escape Lua string-closing delimiters (e.g. quotes/long-bracket terminators), attacker-controlled input in the domain admin 'mydirectory' field can break out of its intended string literal and become executable code - the classic CWE-94 (Improper Control of Generation of Code / 'Code Injection') pattern. The affected component is identified by CPE cpe:2.3:a:wing_ftp_server:wing_ftp_server, and the flaw is a design weakness in the serialization/deserialization path rather than a memory-safety bug.

Know when Wing Ftp Server gets its next vulnerability

Watch products and get an email when something new is published
Check this CVE against your own stack and servers
Exploit and PoC references, threat intelligence from 22 sources

Continue with Google Continue with GitHub

No credit card · 7-day full trial

Severity by source

NVD PRIMARY 8.6 HIGH

CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

vuln.today AI 7.2 HIGH

Network-reachable admin interface (AV:N/AC:L) but requires domain administrator privileges (PR:H) with no user interaction; injected code yields full C/I/A impact within the server process, no scope change.

3.1 AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

4.0 AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Primary rating from NVD.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

Low

Attack Requirements

None

Privileges Required

High

User Interaction

None

Vulnerable system: Confidentiality

High

Vulnerable system: Integrity

High

Vulnerable system: Availability

High

Subsequent system: Confidentiality

None

Subsequent system: Integrity

None

Subsequent system: Availability

None

Lifecycle Timeline

CVSS changed

May 12, 2026 - 21:22 NVD

7.2 (HIGH) 8.6 (HIGH)

CVE Published

May 12, 2026 - 20:43 nvd

HIGH 8.6

DescriptionCVE.org

Wing FTP Server 8.1.2 contains an authenticated remote code execution vulnerability in the session serialization mechanism that allows authenticated administrators to inject arbitrary Lua code through the domain admin mydirectory field. Attackers can exploit unsafe serialization of session values into Lua source code without proper escaping of closing delimiters, causing the injected code to be executed when the poisoned session is loaded via loadfile().

Executive ViewAI

Why It Matters

Wing FTP Server 8.1.2 contains a remote code execution vulnerability exploitable by domain administrators through malicious Lua code injection during session serialization. Attackers with administrator credentials could execute arbitrary code on the file server, risking unauthorized access to sensitive data and business continuity disruption. Immediate mitigation is critical as functional exploit code is publicly available.

Business Impact: High

Compensating Controls

No vendor-released patch identified at time of analysis. Implement: (1) principle of least privilege-restrict domain administrator accounts to FTP-required personnel only; (2) network-level access controls limiting server connections to trusted IP ranges; (3) disable Lua scripting if operations do not require it; (4) enhanced logging and alerting for Lua code execution and session serialization activities; (5) network segmentation isolating affected servers pending alternative solution deployment.

Threat Intelligence Overview

EPSS Score

0.1%

Top 75% exploitable

Prevalence

Medium

commercial multi-protocol FTP server, common in SMB/enterprise file transfer but not ubiquitous

Exploit

POC

Public exploit code exists

Data Quality

7 sources

Confidence: High

EUVD

NVD

CVE.org

EPSS

Vulnrichment

Exploit-DB

VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity HIGH

CISA KEV No

Public POC Yes

EPSS 0.1%

Patch available No

Active threat No

Deciding rule

HIGH severity (CVSS 7.0-8.9)

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision

Scheduled

Exploitation

None

System Exposure· derived

Open

Automatable

Human Impact

High

Technical Impact

Total

Priority Score

Low Medium High Critical

KEV: 0

EPSS: 0

CVSS: +43

PoC: +20

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Code Injection CRITICAL

Code injection occurs when an application accepts user input and passes it directly into a language interpreter or evaluator without proper sanitization.

Remote Code Execution CRITICAL

Remote Code Execution represents the critical moment when an attacker successfully runs arbitrary code on a target system without physical access.