How severe is CVE-2021-30191?

CVE-2021-30191 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-2021-30191 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (59th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-30191?

CVE-2021-30191 primarily affects Codesys V2 Web Server. In total, 28 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-30191?

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-2021-30191 published?

CVE-2021-30191 was published on 2021-05-25 and last updated on 2026-06-17.

CVE-2021-30191

CVE-2021-30191 is a high-severity vulnerability in Codesys V2 Web Server 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-120.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 1% (59th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-120
Affected product: Codesys V2 Web Server
Published: 2021-05-25
Last modified: 2026-06-17

Description

CODESYS V2 Web-Server before 1.1.9.20 has a a Buffer Copy without Checking the Size of the Input.

Frequently asked questions

What is CVE-2021-30191?: CODESYS V2 Web-Server before 1.1.9.20 has a a Buffer Copy without Checking the Size of the Input.
How severe is CVE-2021-30191?: CVE-2021-30191 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-2021-30191 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (59th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-30191?: CVE-2021-30191 primarily affects Codesys V2 Web Server. In total, 28 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-30191?: 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-2021-30191 published?: CVE-2021-30191 was published on 2021-05-25 and last updated on 2026-06-17.

References

Affected products (28)

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:v2_web_server:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:750-823_firmware:*:*:*:*:*:*:*:*

More vulnerabilities in Codesys V2 Web Server

CVE-2021-30193 — Critical (CVSS 9.8): CODESYS V2 Web-Server before 1.1.9.20 has an Out-of-bounds Write.
CVE-2021-30192 — Critical (CVSS 9.8): CODESYS V2 Web-Server before 1.1.9.20 has an Improperly Implemented Security Check.
CVE-2021-30190 — Critical (CVSS 9.8): CODESYS V2 Web-Server before 1.1.9.20 has Improper Access Control.
CVE-2021-30189 — Critical (CVSS 9.8): CODESYS V2 Web-Server before 1.1.9.20 has a Stack-based Buffer Overflow.
CVE-2021-30194 — Critical (CVSS 9.1): CODESYS V2 Web-Server before 1.1.9.20 has an Out-of-bounds Read.

All CVEs affecting Codesys V2 Web Server →

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