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Vulnerability record · CVE-2021-22699 · published 26 May 2021

CVE-2021-22699: Schneider-electric modicon m241 firmware improper input validation vulnerability

Schneider Electric · Modicon M241 Firmware

Improper Input Validation vulnerability exists in Modicon M241/M251 logic controllers firmware prior to V5.1.9.1 that could cause denial of service when specific crafted requests are sent to the controller over HTTP.

7.5 CVSS 3.1 High EPSS 0.98% · top 39.3% CWE-20 · Improper input validation
7.5CVSS 3.1 base score, v2 7.8
0.98%EPSS exploitation probability, 30 days
NoNot in CISA KEV
2Affected product versions listed by NVD
2References
17 Jun 2026Last modified by NVD

Description

Improper Input Validation vulnerability exists in Modicon M241/M251 logic controllers firmware prior to V5.1.9.1 that could cause denial of service when specific crafted requests are sent to the controller over HTTP.

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

Affected products

2 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://download.schneider-electric.com/files?p_Doc_Ref=SEVD-2021-130-05 Vendor Advisory
https://download.schneider-electric.com/files?p_Doc_Ref=SEVD-2021-130-05 Vendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2021-22699), CISA KEV, FIRST EPSS (scores of 2026-09-28). This page is refreshed as NVD updates the record.