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CVE-2021-34593
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.
This record: live connection— last retrieved: 7 November 2026 at 02:05.
Published
26 October 2021
Last modified
17 June 2026
Taken directly from NVD, CISA or the vendor — sometimes in English, unchanged from the source.
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.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
NETWORK
Privileges required
NONE
User interaction
NONE
Confidentiality
None
Integrity
None
Availability
High
Probability of exploitation within 30 days
2.7%
Percentile
86e
Source: FIRST.org, updated on 6 November 2026.
1. Use general security best practices to protect systems from local and network attacks. 2. Do not allow direct access to the device from untrusted networks. 3. Update to the latest firmware according to the table in chapter solutions. 4. Disable the CODESYS 2.3 port 2455.
Our own interpretation and context for the source data above.
IACS Radar assessment
Our own interpretation and context for this vulnerability — not an official source.
IACS Radar priority score
Based on CVSS 7.5, EPSS 2.7%, industrial relevance 75/100.
Combines CVSS, EPSS, KEV status, industrial relevance and exposure relevance — a complement to, not a replacement for, the individual scores below and above.
Conditions for exploitation
Operational impact & energy relevance
Possible loss of visibility of or control over the process upon successful exploitation.
Assessed as relevant to the energy sector based on: Vermeld in een officiële CISA ICS Advisory, wat directe relevantie voor industriële besturingssystemen bevestigt. Productbeschrijving komt overeen met de categorie "PLC", een typisch OT/ICS-componenttype. Vendor "WAGO" is a known supplier of equipment for the energy sector.
Recommended defensive measures
Industrial relevance score
Automatically classified as industrially relevant based on CISA/NVD signals (see reasons).
Classified by IACS Radar-analysepijplijn (geautomatiseerd) on 7 November 2026.
IEC 62443 mapping
Automatic IACS Radar assessment based on the reported CWE weakness classification; not an official certification statement.