Unauthenticated PLC interruption via type-confused read
Published Dec 1, 2025 · Updated Dec 1, 2025
Type confusion in CmpVisuServer in CODESYS Control before 3.5.21.40 or 4.19.0.0 allows remote attackers to interrupt affected PLCs. A crafted Web Visu or remote Target Visu request makes an internal read access a resource through a pointer of the wrong type. No authentication or user interaction is required; Web Visu exposure requires the web server to be running, which by default occurs only when PLC application code includes a visualization.
Summary
What happened
Type confusion in CmpVisuServer in CODESYS Control before 3.5.21.40 or 4.19.0.0 allows remote attackers to interrupt affected PLCs. A crafted Web Visu or remote Target Visu request makes an internal read access a resource through a pointer of the wrong type. No authentication or user interaction is required; Web Visu exposure requires the web server to be running, which by default occurs only when PLC application code includes a visualization.
The record
- CVE
- CVE-2025-41738
- Published
- Dec 1, 2025
- Updated
- Dec 1, 2025
- Vendor
- CODESYS GmbH
- Product
- CODESYS Remote Target Visu
- Classifications
- CWE-843, T1499
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Dec 1, 2025CVE publishedPublication date reported by the CVE source.
- Dec 1, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=3.5.18.0 <3.5.21.40
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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