---
id: CVE-2026-3869
title: >-
  CWE-303 : Incorrect Implementation of Authentication Algorithm vulnerability
  exists that could cause loss of confidentiality, integrity and availability of
  the PLC provided an application project with a lower application level is
  running…
summary: >-
  CWE-303 : Incorrect Implementation of Authentication Algorithm vulnerability
  exists that could cause loss of confidentiality, integrity and availability of
  the PLC provided an application project with a lower application level is
  running…
severity: critical
cvss: 9.2
cvssVector: 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N'
cwe:
  - CWE-303
vendor: Schneider Electric
product: Modicon M580
affected:
  - modicon_m580 All versions with an application level below 4.00
  - modicon_m580_safety All versions with an application level below 4.20
published: '2026-09-11'
updated: '2026-09-18'
sourceUpdated: '2026-09-18T19:30:42.730'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-3869'
references:
  - url: >-
      https://download.se.com/files?p_Doc_Ref=SEVD-2026-251-04&p_enDocType=Security+and+Safety+Notice&p_File_Name=SEVD-2026-251-04.pdf
    label: cybersecurity@se.com
tags:
  - nvd
  - cve.org
epss: 0.00543
epssPercentile: 0.4454
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-09-11T19:14:31.513263Z'
cvssSource: cna
ingestedAt: '2026-09-14T00:35:28.534Z'
---

## Overview

CWE-303 : Incorrect Implementation of Authentication Algorithm vulnerability exists that could cause loss of confidentiality, integrity and availability of the PLC provided an application project with a lower application level is running on the PLC.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.