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

published 2025-12-09 11 mo ago modified 2026-10-07 33 d ago also EUVD-2025-201923

cvss: 7.5; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.5%; EPSS 0.5% chance of exploitation in 30 days, percentile 42%
public exploits: 0; none known

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.

Patch / fix

fixed in 18

Siemens SIMATIC CFU DIQ V2.0.0
Siemens SIMATIC CFU PA V2.0.0
Siemens SIMATIC ET 200SP IM 155-6 PN HA (incl. SIPLUS variants) V1.3
Siemens SIMATIC PN/PN Coupler V6.0.0
Siemens SIMATIC S7-1200 CPU 1211C AC/DC/Rly V4.4.0
Siemens SIMATIC S7-1200 CPU 1211C DC/DC/DC V4.4.0
Siemens SIMATIC S7-1200 CPU 1211C DC/DC/Rly V4.4.0
Siemens SIMATIC S7-1200 CPU 1212C AC/DC/Rly V4.4.0
Siemens SIMATIC S7-1200 CPU 1212C DC/DC/DC V4.4.0
Siemens SIMATIC S7-1200 CPU 1212C DC/DC/Rly V4.4.0
Siemens SIMATIC S7-1200 CPU 1212FC DC/DC/DC V4.4.0
Siemens SIMATIC S7-1200 CPU 1212FC DC/DC/Rly V4.4.0
Siemens SIMATIC S7-1200 CPU 1214C AC/DC/Rly V4.4.0
Siemens SIMATIC S7-1200 CPU 1214C DC/DC/DC V4.4.0
Siemens SIMATIC S7-1200 CPU 1214C DC/DC/Rly V4.4.0
Siemens SIMATIC S7-1200 CPU 1214FC DC/DC/DC V4.4.0
Siemens SIMATIC S7-1200 CPU 1214FC DC/DC/Rly V4.4.0
Siemens SIMATIC S7-1200 CPU 1215C AC/DC/Rly V4.4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

cisa ICSA-25-352-05 updated 2025-12-18 cvss 7.5

Siemens Interniche IP-Stack

Siemens SIDOOR ATD430W Siemens SIDOOR ATE530G COATED (6FB1221-5SM10-7BP0) Siemens SIDOOR ATE530S COATED
affected: workaround, no fix planned
Siemens SIMATIC CFU DIQ (6ES7655-5PX31-1XX0) < 2.0.0 Siemens SIMATIC CFU PA (6ES7655-5PX11-0XX0) < 2.0.0
affected: fixed in V2.0.0, workaround support.industry.siemens.com
Siemens SIMATIC CFU PA (6ES7655-5PX11-1XX0) < 2.0.0
affected: fixed in V2.0.0, workaround support.industry.siemens.com
Siemens SIMATIC ET 200AL IM 157-1 PN (6ES7157-1AB00-0AB0) Siemens SIMATIC ET 200clean, CM 8x IO-Link (6ES7148-7JH00-0BB0) Siemens SIMATIC ET 200clean, DI 16x24VDC (6ES7141-7BH00-0BB0) Siemens SIMATIC ET 200clean, DIQ 16x24VDC/0,5A (6ES7143-7BH00-0BB0) Siemens SIMATIC ET 200eco PN, AI 8xRTD/TC, M12-L (6ES7144-6JF00-0BB0) >= 5.1.1 Siemens SIMATIC ET 200eco PN, CM 4x IO-Link, M12-L (6ES7148-6JE00-0BB0) >= 5.1.1

+18 more productsfewer

Siemens SIMATIC ET 200eco PN, CM 8x IO-Link, M12-L (6ES7148-6JG00-0BB0) >= 5.1.1 Siemens SIMATIC ET 200eco PN, CM 8x IO-Link, M12-L (6ES7148-6JJ00-0BB0) >= 5.1.1 Siemens SIMATIC ET 200eco PN, DI 8x24VDC, M12-L (6ES7141-6BG00-0BB0) >= 5.1.1 Siemens SIMATIC ET 200eco PN, DI 16x24VDC, M12-L (6ES7141-6BH00-0BB0) >= 5.1.1 Siemens SIMATIC ET 200eco PN, DIQ 16x24VDC/2A, M12-L (6ES7143-6BH00-0BB0) >= 5.1.1 Siemens SIMATIC ET 200eco PN, DQ 8x24VDC/0,5A, M12-L (6ES7142-6BG00-0BB0) >= 5.1.1 Siemens SIMATIC ET 200eco PN, DQ 8x24VDC/2A, M12-L (6ES7142-6BR00-0BB0) >= 5.1.1 Siemens SIMATIC ET 200MP IM 155-5 PN HF (6ES7155-5AA00-0AC0) >= 4.2.0 Siemens SIMATIC ET 200pro IM 154-8 PN/DP CPU (6ES7154-8AB01-0AB0) Siemens SIMATIC ET 200pro IM 154-8F PN/DP CPU (6ES7154-8FB01-0AB0) Siemens SIMATIC ET 200pro IM 154-8FX PN/DP CPU (6ES7154-8FX00-0AB0) Siemens SIMATIC ET 200S IM 151-8 PN/DP CPU (6ES7151-8AB01-0AB0) Siemens SIMATIC ET 200S IM 151-8F PN/DP CPU (6ES7151-8FB01-0AB0) Siemens SIMATIC ET 200SP CPU 1510SP F-1 PN (6ES7510-1SJ00-0AB0) Siemens SIMATIC ET 200SP CPU 1510SP-1 PN (6ES7510-1DJ00-0AB0) Siemens SIMATIC ET 200SP CPU 1512SP F-1 PN (6ES7512-1SK00-0AB0) Siemens SIMATIC ET 200SP CPU 1512SP-1 PN (6ES7512-1DK00-0AB0) Siemens SIMATIC ET 200SP IM 155-6 MF HF (6ES7155-6MU00-0CN0)

affected: workaround, no fix planned
Siemens SIMATIC ET 200SP IM 155-6 PN HA (incl. SIPLUS variants) < 1.3
affected: fixed in V1.3, workaround
Siemens SIMATIC ET 200SP IM 155-6 PN HF (6ES7155-6AU00-0CN0) >= 4.2.0 Siemens SIMATIC ET 200SP IM 155-6 PN/2 HF (6ES7155-6AU01-0CN0) >= 4.2.0 Siemens SIMATIC ET 200SP IM 155-6 PN/3 HF (6ES7155-6AU30-0CN0) >= 4.2.0 Siemens SIMATIC PN/MF Coupler (6ES7158-3MU10-0XA0)
affected: workaround, no fix planned
Siemens SIMATIC PN/PN Coupler (6ES7158-3AD10-0XA0) < 6.0.0
affected: fixed in V6.0.0, workaround support.industry.siemens.com
Siemens SIMATIC Power Line Booster PLB, Base Module (6ES7972-5AA10-0AB0) Siemens SIMATIC Power Line Booster PLB, Modem Module ST (6ES7972-5AA51-0AB0)
affected: workaround, no fix planned

show 1 more

Siemens SIMATIC S7-200 SMART CPU CR40 (6ES7288-1CR40-0AA0) Siemens SIMATIC S7-200 SMART CPU CR60 (6ES7288-1CR60-0AA0)
affected: workaround, no fix available

131 more affected in the full advisory

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

CISA SSVC

Exploitation: none
Automatable: yes
Technical impact: partial
Assessed: 11 mo ago (2025-12-09)

Exploit prediction

0.49% chance of exploitation in the next 30 days, higher than 42% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA	4.0	8.7	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
CNA	4.0	8.7	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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X