CVE-2025-40820
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. 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.
Scoring
- Severity
- HIGH
- CVSS base score
- 8.7
- CVSS vector
- CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- EPSS probability
- 0.49%
- CWE
- CWE-940
- Published
- 2025-12-09
- Last modified
- 2026-03-12
Affected products
- Siemens SIDOOR ATD430W
- Siemens SIDOOR ATE530G COATED
- Siemens SIDOOR ATE530S COATED
- Siemens SIMATIC CFU DIQ
- Siemens SIMATIC CFU PA
- Siemens SIMATIC ET 200AL IM 157-1 PN
- Siemens SIMATIC ET 200clean, CM 8x IO-Link
- Siemens SIMATIC ET 200clean, DI 16x24VDC
Weakness type
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