How severe is CVE-2026-3869?

CVE-2026-3869 has a CVSS 4.0 base score of 9.2, rated critical severity.

Is CVE-2026-3869 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (44th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-3869?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2026-3869 published?

CVE-2026-3869 was published on 2026-09-11 and last updated on 2026-09-18.

CVE-2026-3869

CVE-2026-3869 is a critical-severity vulnerability with a CVSS 4.0 base score of 9.2. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-303.

Key facts

Severity: Critical (CVSS 4.0 base score 9.2)
EPSS exploit prediction: 1% (44th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-303
Published: 2026-09-11
Last modified: 2026-09-18

Description

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.

Frequently asked questions

What is CVE-2026-3869?: 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.
How severe is CVE-2026-3869?: CVE-2026-3869 has a CVSS 4.0 base score of 9.2, rated critical severity.
Is CVE-2026-3869 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (44th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-3869?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2026-3869 published?: CVE-2026-3869 was published on 2026-09-11 and last updated on 2026-09-18.

References

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

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