How severe is CVE-2021-30186?

CVE-2021-30186 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-30186 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 7% (94th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-30186?

CVE-2021-30186 primarily affects Codesys Plcwinnt. In total, 29 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-30186?

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

When was CVE-2021-30186 published?

CVE-2021-30186 was published on 2021-05-25 and last updated on 2026-06-17.

CVE-2021-30186

CVE-2021-30186 is a high-severity vulnerability in Codesys Plcwinnt with a CVSS 3.x base score of 7.5. 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-787.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 7% (94th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-787
Affected product: Codesys Plcwinnt
Published: 2021-05-25
Last modified: 2026-06-17

Description

CODESYS V2 runtime system SP before 2.4.7.55 has a Heap-based Buffer Overflow.

Frequently asked questions

What is CVE-2021-30186?: CODESYS V2 runtime system SP before 2.4.7.55 has a Heap-based Buffer Overflow.
How severe is CVE-2021-30186?: CVE-2021-30186 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-30186 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 7% (94th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-30186?: CVE-2021-30186 primarily affects Codesys Plcwinnt. In total, 29 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-30186?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-30186 published?: CVE-2021-30186 was published on 2021-05-25 and last updated on 2026-06-17.

References

Affected products (29)

cpe:2.3:o:wago:750-893_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-891_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-890_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-889_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-885_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-882_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-881_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-880_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-862_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-852_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-832_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-831_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-829_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-8202_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-8203_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-8204_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-8206_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-8207_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-8208_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-8210_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-8211_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-8212_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-8213_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-8214_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-8216_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-8217_firmware:*:*:*:*:*:*:*:*
cpe:2.3:a:codesys:plcwinnt:*:*:*:*:*:*:*:*
cpe:2.3:a:codesys:runtime_toolkit:*:*:*:*:*:*:x86:*
cpe:2.3:o:wago:750-823_firmware:*:*:*:*:*:*:*:*

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