# Missing authentication in Siemens SIMATIC CP 1542SP-1 and others

CVE record · `CVE-2025-40771`

- **Identifiers:** `CVE-2025-40771`
- **State:** Confirmed
- **Severity:** CVSS 9.3 Critical
- **Critical:** Yes: CVSS 9+
- **CNA:** siemens
- **Weakness (CWE):** [CWE-306](https://cwe.mitre.org/data/definitions/306.html)
- **Tags:** [Authentication bypass](https://agentprime.io/advisories/tag/auth-bypass.md)
- **Technologies:** [Siemens SIMATIC CP 1542SP-1](https://agentprime.io/advisories/technology/siemens-simatic-cp-1542sp-1.md) · [Siemens SIMATIC CP 1542SP-1 IRC](https://agentprime.io/advisories/technology/siemens-simatic-cp-1542sp-1-irc.md) · [Siemens SIMATIC CP 1543SP-1](https://agentprime.io/advisories/technology/siemens-simatic-cp-1543sp-1.md) · [Siemens SIPLUS ET 200SP CP 1542SP-1 IRC TX RAIL](https://agentprime.io/advisories/technology/siemens-siplus-et-200sp-cp-1542sp-1-irc-tx-rail.md) · [Siemens SIPLUS ET 200SP CP 1543SP-1 ISEC](https://agentprime.io/advisories/technology/siemens-siplus-et-200sp-cp-1543sp-1-isec.md) · [Siemens SIPLUS ET 200SP CP 1543SP-1 ISEC TX RAIL](https://agentprime.io/advisories/technology/siemens-siplus-et-200sp-cp-1543sp-1-isec-tx-rail.md)
- **Published:** 14 Oct 2025
- **Updated:** 14 Oct 2025
- **Reviewed by a person:** No

Published by the CVE Program (CNA: siemens) at 14 Oct 2025, 09:15 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.

## Critical

Critical, because:

- CVSS score 9.3: 9.0 or more.

How we decide what’s critical: <https://agentprime.io/advisories/critical.md>

## Affected products, as the CNA wrote them

- Vendor: Siemens. Product: SIMATIC CP 1542SP-1.
  - affected: `before V2.4.24` (custom)
  - Other versions: unknown
- Vendor: Siemens. Product: SIMATIC CP 1542SP-1 IRC.
  - affected: `before V2.4.24` (custom)
  - Other versions: unknown
- Vendor: Siemens. Product: SIMATIC CP 1543SP-1.
  - affected: `before V2.4.24` (custom)
  - Other versions: unknown
- Vendor: Siemens. Product: SIPLUS ET 200SP CP 1542SP-1 IRC TX RAIL.
  - affected: `before V2.4.24` (custom)
  - Other versions: unknown
- Vendor: Siemens. Product: SIPLUS ET 200SP CP 1543SP-1 ISEC.
  - affected: `before V2.4.24` (custom)
  - Other versions: unknown
- Vendor: Siemens. Product: SIPLUS ET 200SP CP 1543SP-1 ISEC TX RAIL.
  - affected: `before V2.4.24` (custom)
  - Other versions: unknown

## 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

- 9.8 Critical, CVSS 3.1: `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`, from CNA (siemens)
- 9.3 Critical, CVSS 4.0: `CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`, from CNA (siemens) (used for this record)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0053, the 44th 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 14 Oct 2025. New records show when each source confirmed them.

## Sources

- [CVE List: CVE-2025-40771](https://www.cve.org/CVERecord?id=CVE-2025-40771)
- [NVD: CVE-2025-40771](https://nvd.nist.gov/vuln/detail/CVE-2025-40771)

### References from the CNA

- <https://cert-portal.siemens.com/productcert/html/ssa-486936.html>

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 (<https://api.agentprime.io/mcp>), `get_advisory` returns this record and `search_advisories` finds related ones. Setup: <https://agentprime.io/mcp.md>
- As JSON: <https://api.agentprime.io/v1/advisories/CVE-2025-40771>
- Everything that needs attention now: <https://agentprime.io/advisories/critical.md>

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The web page: <https://agentprime.io/advisories/CVE-2025-40771/>. Everything for agents: <https://agentprime.io/llms.txt>.