Communication-task crash via SysSocketSelect race
Published Dec 1, 2025 · Updated Jan 7, 2026
Out-of-bounds read in CODESYS runtime products allows remote attackers to crash communication tasks via crafted socket traffic. The poll-based SysSocketSelect() implementation incorrectly handles internal state during concurrent caller interaction, causing a read beyond the intended bounds. Exploitation requires winning a race condition; the resulting crash interrupts PLC operation or PLCHandler-based monitoring.
Summary
What happened
Out-of-bounds read in CODESYS runtime products allows remote attackers to crash communication tasks via crafted socket traffic. The poll-based SysSocketSelect() implementation incorrectly handles internal state during concurrent caller interaction, causing a read beyond the intended bounds. Exploitation requires winning a race condition; the resulting crash interrupts PLC operation or PLCHandler-based monitoring.
The record
- CVE
- CVE-2025-41739
- Published
- Dec 1, 2025
- Updated
- Jan 7, 2026
- Vendor
- CODESYS GmbH
- Product
- CODESYS Remote Target Visu
- Classifications
- CWE-125, T0814
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Dec 1, 2025CVE publishedPublication date reported by the CVE source.
- Jan 7, 2026Record 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=3.5.21.0 <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
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Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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