CVE-2025-40820
Published: 09 December 2025
Summary
CVE-2025-40820 is a high-severity Improper Verification of Source of a Communication Channel (CWE-940) vulnerability in Siemens (inferred from references). Its CVSS base score is 8.7 (High).
Operationally, ranked at the 28.0th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2025-201923
Vulnerability details
Affected products do not properly enforce TCP sequence number validation in specific scenarios but accept values within a broad range. This could allow an unauthenticated remote attacker e.g. to interfere with connection setup, potentially leading to a denial of service.…
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The attack succeeds only if an attacker can inject IP packets with spoofed addresses at precisely timed moments, and it affects only TCP-based services.
- CWE(s)
Related Threats
No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.
Affected Assets
Mitigating Controls
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Enforces verification of the source of a communication channel by requiring identification and authentication of services first.
Requires explicit verification of the source and integrity of the channel used for authentication and other security functions.
Provides the means to verify the source of name-resolution responses instead of relying on unauthenticated channels.
Requires explicit verification of the communication source, blocking session hijacking via spoofed or alternate channels.