Security readout for executives and security teams
Plain-English summary
A malicious trace file could make a legitimate Siemens PLC web user perform actions they are allowed to perform. The attack depends on social engineering a user with the "Read diagnostics" right into importing the file. Because PLC operations may be triggered through the webserver, the business risk is high for exposed operational environments.
Executive priority
Prioritize this for OT environments because the CVSS score is critical and the described outcome can affect PLC operations. Immediate focus should be exposure reduction, role review, and vendor-guidance tracking rather than assuming exploitation is already occurring.
Technical view
CVE-2025-40943 is an insufficient sanitization issue in trace-file handling on listed Siemens SIMATIC controller products. Imported crafted trace content can execute malicious code in the authorized client browser session and use that session to trigger PLC operations via the device webserver. The record lists CWE-95 and CVSS 3.1 score 9.6.
Likely exposure
Exposure is most likely where affected Siemens SIMATIC Drive Controller, ET 200SP, Open Controller, or S7-1500 models use webserver diagnostics workflows and users can import trace files. Exact affected version ranges are unclear in the bundle because versions are listed only as "0" with unknown default status.
Exploitation context
The bundle does not show known active exploitation, and KEV is false. Exploitation requires user interaction: an attacker must persuade an authorized user with "Read diagnostics" rights to import a crafted trace file. Impact may include confidentiality, integrity, and availability consequences through authorized PLC operations.
Researcher notes
Evidence supports a browser-session code injection path through crafted trace-file import, but the bundle lacks fixed-version details, proof-of-concept status, and specific Siemens remediation text. Do not generalize beyond the listed SIMATIC products without consulting SSA-452276 and the CVE record.
Mitigation direction
- Review Siemens SSA-452276 for official updates, version guidance, and mitigations.
- Limit "Read diagnostics" rights to users who operationally require them.
- Restrict access to PLC webservers from untrusted networks.
- Treat externally supplied trace files as untrusted and avoid importing them.
- Educate authorized users about malicious diagnostic trace-file handling.
Validation and detection
- Inventory listed Siemens SIMATIC controller models in operational environments.
- Identify users and roles with the "Read diagnostics" function right.
- Confirm whether PLC webservers are reachable from non-administrative networks.
- Review procedures for importing diagnostic trace files.
- Check Siemens advisory status for each deployed model and firmware version.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-95: Code execution behavior lookup
Code execution and unsafe deserialization weaknesses often justify reviewing execution behavior and process telemetry. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2025-40943 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Critical
- CVSS
- 9.6 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
2 official scoresWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H2.86siemensCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H——siemensVulnerability scoring details
Base CVSS 4.0 score
9.4CriticalVector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
Base CVSS 3.1 score
9.6CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://cert-portal.siemens.com/productcert/html/ssa-452276.htmlCVE reference, siemens
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Neutralization of Directives in Dynamically Evaluated Code ('Eval Injection')
Improper Neutralization of Directives in Dynamically Evaluated Code ('Eval Injection') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.