What is CVE-2021-30186?

CVE-2021-30186 is a high-severity vulnerability in Codesys Plcwinnt, classified under Out-of-bounds Write. CVSS score: 7.5/10. Published 2021-05-25.

How severe is CVE-2021-30186?

High severity. CVSS v3 base score is 7.5 out of 10.

Is CVE-2021-30186 known to be exploited?

1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Buffer overflow in Codesys Plcwinnt

CVE-2021-30186

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

Vulnerability class: Buffer Overflow

Published 2021-05-25 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.074 (94.2th percentile), scored 2026-09-29.

Low probability of exploitation in the next 30 days, but still tracked. 94th percentile — 94.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.074 · newest: 0.074 · change: 0.000

Affected products

Weakness classification (CWE)

CWE-787 — Out-of-bounds Write

Public proof-of-concept exploits

yossireuven/Publications

References

customers.codesys.com/index.php (Permissions Required, Vendor Advisory)
customers.codesys.com/index.php (Vendor Advisory)

Frequently asked questions

What is CVE-2021-30186?: CVE-2021-30186 is a high-severity vulnerability in Codesys Plcwinnt, classified under Out-of-bounds Write. CVSS score: 7.5/10. Published 2021-05-25.
How severe is CVE-2021-30186?: High severity. CVSS v3 base score is 7.5 out of 10.
Is CVE-2021-30186 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.