How severe is CVE-2021-30194?

CVE-2021-30194 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability high.

Is CVE-2021-30194 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (63rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-30194?

CVE-2021-30194 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-2021-30194?

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-2021-30194 published?

CVE-2021-30194 was published on 2021-05-25 and last updated on 2026-06-17.

CVE-2021-30194

CVE-2021-30194 is a critical-severity vulnerability in Codesys V2 Web Server with a CVSS 3.x base score of 9.1. 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-125.

Key facts

Severity: Critical (CVSS 3.x base score 9.1)
CVSS v2: 6.4
EPSS exploit prediction: 1% (63rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-125
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 an Out-of-bounds Read.

Frequently asked questions

What is CVE-2021-30194?: CODESYS V2 Web-Server before 1.1.9.20 has an Out-of-bounds Read.
How severe is CVE-2021-30194?: CVE-2021-30194 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability high.
Is CVE-2021-30194 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (63rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-30194?: CVE-2021-30194 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-2021-30194?: 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-2021-30194 published?: CVE-2021-30194 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-2021-30191 — High (CVSS 7.5): CODESYS V2 Web-Server before 1.1.9.20 has a a Buffer Copy without Checking the Size of the Input.

All CVEs affecting Codesys V2 Web Server →

Other CWE-125 (Out-of-bounds Read) vulnerabilities

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CVE-2024-22004 — Critical (CVSS 10.0): Due to length check, an attacker with privilege access on a Linux Nonsecure operating system can trigger a…
CVE-2021-41556 — Critical (CVSS 10.0): sqclass.cpp in Squirrel through 2.2.5 and 3.x through 3.1 allows an out-of-bounds read (in the core interpreter) that…
CVE-2021-21777 — Critical (CVSS 10.0): An information disclosure vulnerability exists in the Ethernet/IP UDP handler functionality of EIP Stack Group OpENer…
CVE-2017-14451 — Critical (CVSS 10.0): An exploitable out-of-bounds read vulnerability exists in libevm (Ethereum Virtual Machine) of CPP-Ethereum. A…
CVE-2013-0767 — Critical (CVSS 10.0): The nsSVGPathElement::GetPathLengthScale function in Mozilla Firefox before 18.0, Firefox ESR 10.x before 10.0.12 and…

Browse all CWE-125 (Out-of-bounds Read) vulnerabilities →