# Affected products do not properly enforce TCP sequence number validation in specific scenarios but accept values within a broad range. CVE record · `CVE-2025-40820` - **Identifiers:** `CVE-2025-40820` - **State:** Confirmed - **Severity:** CVSS 8.7 High - **Critical:** No - **CNA:** siemens - **Weakness (CWE):** [CWE-940](https://cwe.mitre.org/data/definitions/940.html) - **Tags:** [CWE-940](https://agentprime.io/advisories/tag/cwe-940.md) - **Technologies:** [Siemens SIDOOR ATD430W](https://agentprime.io/advisories/technology/siemens-sidoor-atd430w.md) · [Siemens SIDOOR ATE530G COATED](https://agentprime.io/advisories/technology/siemens-sidoor-ate530g-coated.md) · [Siemens SIDOOR ATE530S COATED](https://agentprime.io/advisories/technology/siemens-sidoor-ate530s-coated.md) · [Siemens SIMATIC CFU DIQ](https://agentprime.io/advisories/technology/siemens-simatic-cfu-diq.md) · [Siemens SIMATIC CFU PA](https://agentprime.io/advisories/technology/siemens-simatic-cfu-pa.md) · [Siemens SIMATIC ET 200AL IM 157-1 PN](https://agentprime.io/advisories/technology/siemens-simatic-et-200al-im-157-1-pn.md) · [Siemens SIMATIC ET 200clean, CM 8x IO-Link](https://agentprime.io/advisories/technology/siemens-simatic-et-200clean-cm-8x-io-link.md) · [Siemens SIMATIC ET 200clean, DI 16x24VDC](https://agentprime.io/advisories/technology/siemens-simatic-et-200clean-di-16x24vdc.md) · [Siemens SIMATIC ET 200clean, DIQ 16x24VDC/0,5A](https://agentprime.io/advisories/technology/siemens-simatic-et-200clean-diq-16x24vdc-0-5a.md) · [Siemens SIMATIC ET 200eco PN, AI 8xRTD/TC, M12-L](https://agentprime.io/advisories/technology/siemens-simatic-et-200eco-pn-ai-8xrtd-tc-m12-l.md) · [Siemens SIMATIC ET 200eco PN, CM 4x IO-Link, M12-L](https://agentprime.io/advisories/technology/siemens-simatic-et-200eco-pn-cm-4x-io-link-m12-l.md) · [Siemens SIMATIC ET 200eco PN, CM 8x IO-Link, M12-L](https://agentprime.io/advisories/technology/siemens-simatic-et-200eco-pn-cm-8x-io-link-m12-l.md) · [Siemens SIMATIC ET 200eco PN, DI 16x24VDC, M12-L](https://agentprime.io/advisories/technology/siemens-simatic-et-200eco-pn-di-16x24vdc-m12-l.md) · [Siemens SIMATIC ET 200eco PN, DI 8x24VDC, M12-L](https://agentprime.io/advisories/technology/siemens-simatic-et-200eco-pn-di-8x24vdc-m12-l.md) · [Siemens SIMATIC ET 200eco PN, DIQ 16x24VDC/2A, M12-L](https://agentprime.io/advisories/technology/siemens-simatic-et-200eco-pn-diq-16x24vdc-2a-m12-l.md) · [Siemens SIMATIC ET 200eco PN, DQ 8x24VDC/0,5A, M12-L](https://agentprime.io/advisories/technology/siemens-simatic-et-200eco-pn-dq-8x24vdc-0-5a-m12-l.md) · [Siemens SIMATIC ET 200eco PN, DQ 8x24VDC/2A, M12-L](https://agentprime.io/advisories/technology/siemens-simatic-et-200eco-pn-dq-8x24vdc-2a-m12-l.md) · [Siemens SIMATIC ET 200MP IM 155-5 PN HF](https://agentprime.io/advisories/technology/siemens-simatic-et-200mp-im-155-5-pn-hf.md) · [Siemens SIMATIC ET 200pro IM 154-8 PN/DP CPU](https://agentprime.io/advisories/technology/siemens-simatic-et-200pro-im-154-8-pn-dp-cpu.md) · [Siemens SIMATIC ET 200pro IM 154-8F PN/DP CPU](https://agentprime.io/advisories/technology/siemens-simatic-et-200pro-im-154-8f-pn-dp-cpu.md) - **Published:** 9 Dec 2025 - **Updated:** 9 Dec 2025 - **Reviewed by a person:** No Published by the CVE Program (CNA: siemens) at 9 Dec 2025, 10:44 UTC. agentprime has not analysed this yet, so whether it affects any app is not known. This CVE names a vendor and product rather than a package, so the lockfile check doesn’t match it. ## Affected products, as the CNA wrote them - Vendor: Siemens. Product: SIDOOR ATD430W. - affected: `before *` (custom) - Other versions: unknown - Vendor: Siemens. Product: SIDOOR ATE530G COATED. - affected: `before *` (custom) - Other versions: unknown - Vendor: Siemens. Product: SIDOOR ATE530S COATED. - affected: `before *` (custom) - Other versions: unknown - Vendor: Siemens. Product: SIMATIC CFU DIQ. - affected: `before V2.0.0` (custom) - Other versions: unknown - Vendor: Siemens. Product: SIMATIC CFU PA. - affected: `before V2.0.0` (custom) - Other versions: unknown - Vendor: Siemens. Product: SIMATIC CFU PA. - affected: `before V2.0.0` (custom) - Other versions: unknown - Vendor: Siemens. Product: SIMATIC ET 200AL IM 157-1 PN. - affected: `before *` (custom) - Other versions: unknown - Vendor: Siemens. Product: SIMATIC ET 200clean, CM 8x IO-Link. - affected: `before *` (custom) - Other versions: unknown - Vendor: Siemens. Product: SIMATIC ET 200clean, DI 16x24VDC. - affected: `before *` (custom) - Other versions: unknown - Vendor: Siemens. Product: SIMATIC ET 200clean, DIQ 16x24VDC/0,5A. - affected: `before *` (custom) - Other versions: unknown - Vendor: Siemens. Product: SIMATIC ET 200eco PN, AI 8xRTD/TC, M12-L. - affected: `V5.1.1 to before *` (custom) - Other versions: unknown - Vendor: Siemens. Product: SIMATIC ET 200eco PN, CM 4x IO-Link, M12-L. - affected: `V5.1.1 to before *` (custom) - Other versions: unknown - Vendor: Siemens. Product: SIMATIC ET 200eco PN, CM 8x IO-Link, M12-L. - affected: `V5.1.1 to before *` (custom) - Other versions: unknown - Vendor: Siemens. Product: SIMATIC ET 200eco PN, CM 8x IO-Link, M12-L. - affected: `V5.1.1 to before *` (custom) - Other versions: unknown - Vendor: Siemens. Product: SIMATIC ET 200eco PN, DI 16x24VDC, M12-L. - affected: `V5.1.1 to before *` (custom) - Other versions: unknown - Vendor: Siemens. Product: SIMATIC ET 200eco PN, DI 8x24VDC, M12-L. - affected: `V5.1.1 to before *` (custom) - Other versions: unknown - Vendor: Siemens. Product: SIMATIC ET 200eco PN, DIQ 16x24VDC/2A, M12-L. - affected: `V5.1.1 to before *` (custom) - Other versions: unknown - Vendor: Siemens. Product: SIMATIC ET 200eco PN, DQ 8x24VDC/0,5A, M12-L. - affected: `V5.1.1 to before *` (custom) - Other versions: unknown - Vendor: Siemens. Product: SIMATIC ET 200eco PN, DQ 8x24VDC/2A, M12-L. - affected: `V5.1.1 to before *` (custom) - Other versions: unknown - Vendor: Siemens. Product: SIMATIC ET 200MP IM 155-5 PN HF. - affected: `V4.2.0 to before *` (custom) - Other versions: unknown - Vendor: Siemens. Product: SIMATIC ET 200pro IM 154-8 PN/DP CPU. - affected: `before *` (custom) - Other versions: unknown - Vendor: Siemens. Product: SIMATIC ET 200pro IM 154-8F PN/DP CPU. - affected: `before *` (custom) - Other versions: unknown - Vendor: Siemens. Product: SIMATIC ET 200pro IM 154-8FX PN/DP CPU. - affected: `before *` (custom) - Other versions: unknown - Vendor: Siemens. Product: SIMATIC ET 200S IM 151-8 PN/DP CPU. - affected: `before *` (custom) - Other versions: unknown - Vendor: Siemens. Product: SIMATIC ET 200S IM 151-8F PN/DP CPU. - affected: `before *` (custom) - Other versions: unknown - Vendor: Siemens. Product: SIMATIC ET 200SP CPU 1510SP F-1 PN. - affected: `before *` (custom) - Other versions: unknown - Vendor: Siemens. Product: SIMATIC ET 200SP CPU 1510SP-1 PN. - affected: `before *` (custom) - Other versions: unknown - Vendor: Siemens. Product: SIMATIC ET 200SP CPU 1512SP F-1 PN. - affected: `before *` (custom) - Other versions: unknown - Vendor: Siemens. Product: SIMATIC ET 200SP CPU 1512SP-1 PN. - affected: `before *` (custom) - Other versions: unknown - Vendor: Siemens. Product: SIMATIC ET 200SP IM 155-6 MF HF. - affected: `before *` (custom) - Other versions: unknown - Vendor: Siemens. Product: SIMATIC ET 200SP IM 155-6 PN HA (incl. SIPLUS variants). - affected: `before V1.3` (custom) - Other versions: unknown - Vendor: Siemens. Product: SIMATIC ET 200SP IM 155-6 PN HF. - affected: `V4.2.0 to before *` (custom) - Other versions: unknown - Vendor: Siemens. Product: SIMATIC ET 200SP IM 155-6 PN/2 HF. - affected: `V4.2.0 to before *` (custom) - Other versions: unknown - Vendor: Siemens. Product: SIMATIC ET 200SP IM 155-6 PN/3 HF. - affected: `V4.2.0 to before *` (custom) - Other versions: unknown - Vendor: Siemens. Product: SIMATIC PN/MF Coupler. - affected: `before *` (custom) - Other versions: unknown - Vendor: Siemens. Product: SIMATIC PN/PN Coupler. - affected: `before V6.0.0` (custom) - Other versions: unknown - Vendor: Siemens. Product: SIMATIC Power Line Booster PLB, Base Module. - affected: `before *` (custom) - Other versions: unknown - Vendor: Siemens. Product: SIMATIC Power Line Booster PLB, Modem Module ST. - affected: `before *` (custom) - Other versions: unknown - Vendor: Siemens. Product: SIMATIC S7-1200 CPU 1211C AC/DC/Rly. - affected: `before V4.4.0` (custom) - Other versions: unknown - Vendor: Siemens. Product: SIMATIC S7-1200 CPU 1211C DC/DC/DC. - affected: `before V4.4.0` (custom) - Other versions: unknown And 131 more products. The full list is on the CVE record: ## Not analysed yet We haven’t published our own analysis of this CVE. If a person reviews it, this page will say what’s affected and what has to be true for it to matter. ## Severity and exploitation - 7.5 High, CVSS 3.1: `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`, from CNA (siemens) - 8.7 High, CVSS 4.0: `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`, from CNA (siemens) (used for this record) - **CISA KEV:** Not listed. - **EPSS:** 0.0049, the 42nd percentile, on 6 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days. ## Timeline This record came from the full history of the CVE Program, published 9 Dec 2025. New records show when each source confirmed them. ## Sources - [CVE List: CVE-2025-40820](https://www.cve.org/CVERecord?id=CVE-2025-40820) - [NVD: CVE-2025-40820](https://nvd.nist.gov/vuln/detail/CVE-2025-40820) ### References from the CNA - Facts on this page come from the CVE List as the CNA published them, with CVSS from the sources named above, CISA KEV and FIRST EPSS. Vendors, products and versions are shown as the CNA wrote them. We don’t reproduce the CVE’s description. ## Check whether this affects you This CVE names a vendor and product rather than a package, so the lockfile check doesn’t match it. Compare the affected versions above with what you run. - With the agentprime MCP server (), `get_advisory` returns this record and `search_advisories` finds related ones. Setup: - As JSON: - Everything that needs attention now: --- The web page: . Everything for agents: .