CVE-2021-34593
HIGHEPSS 84th pctlDescription
In CODESYS V2 Runtime Toolkit 32 Bit full and PLCWinNT prior to versions V2.4.7.56 unauthenticated crafted invalid requests may result in several denial-of-service conditions. Running PLC programs may be stopped, memory may be leaked, or further communication clients may be blocked from accessing the PLC.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Exploit Intelligence
Elevated risk: more likely to be exploited than 84% of all known CVEs.
References
Related Vulnerabilities
Other CWE-755 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2017-5638 | Critical | 9.8 | 100% | KEV + Ransom | Fix |
| CVE-2020-7247 | Critical | 9.8 | 99% | KEV | Fix |
| CVE-2023-36933 | High | 7.5 | 72% | - | Fix |
| CVE-2018-0934 | High | 7.5 | 67% | - | Fix |
| CVE-2019-14287 | High | 8.8 | 64% | - | Fix |
| CVE-2019-12815 | Critical | 9.8 | 58% | - | Fix |
Common questions
How do I fix CVE-2021-34593?
Published advisories record a fix for 15 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.
Is CVE-2021-34593 being actively exploited?
Not that we know of. CVE-2021-34593 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 2.6% is the estimated probability that it will be exploited in the next 30 days. That is higher than 84% of all scored CVEs.
How severe is CVE-2021-34593?
CVE-2021-34593 has a CVSS v3 base score of 7.5, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2021-34593 affect?
Published advisories record a fix for 750-8202 firmware (NVD), 750-8203 firmware (NVD), 750-8204 firmware (NVD), 750-8206 firmware (NVD), and 11 more. Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-08-15.