High 7.5Published Dec 9, 2025

CVE-2025-40820Affected products do not properly enforce TCP sequence number validation in specific scenarios but accept values within a broad range.

Updated under an hour ago (Oct 28, 2026, 8:50 AM ET)

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It affects Siemens SIDOOR ATD430W and 59 other products. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for Siemens SIDOOR ATD430W

Exploited in the last 30 days

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.

CVSS: 7.5 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): CWE-940
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: siemens
NVD analysis: Deferred
Record last updated: Dec 9, 2025
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Siemens SIDOOR ATD430W siemens:sidoor_atd430w (from the name)	all versions	CNA record
Siemens SIDOOR ATE530G COATED siemens:sidoor_ate530g_coated (from the name)	all versions	CNA record
Siemens SIDOOR ATE530S COATED siemens:sidoor_ate530s_coated (from the name)	all versions	CNA record
Siemens SIMATIC CFU DIQ siemens:simatic_cfu_diq (from the name)	before V2.0.0	CNA record
Siemens SIMATIC CFU PA siemens:simatic_cfu_pa (from the name)	before V2.0.0	CNA record
Siemens SIMATIC ET 200AL IM 157-1 PN siemens:simatic_et_200al_im_157_1_pn (from the name)	all versions	CNA record
Siemens SIMATIC ET 200clean, CM 8x IO-Link siemens:simatic_et_200clean_cm_8x_io_link (from the name)	all versions	CNA record
Siemens SIMATIC ET 200clean, DI 16x24VDC siemens:simatic_et_200clean_di_16x24vdc (from the name)	all versions	CNA record
Siemens SIMATIC ET 200clean, DIQ 16x24VDC/0,5A siemens:simatic_et_200clean_diq_16x24vdc_0_5a (from the name)	all versions	CNA record
Siemens SIMATIC ET 200eco PN, AI 8xRTD/TC, M12-L siemens:simatic_et_200eco_pn_ai_8xrtd_tc_m12_l (from the name)	from V5.1.1	CNA record
1–10 of 60

References

References

https://cert-portal.siemens.com/productcert/html/ssa-915282.html

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.