SIMATIC S7-PLCSIM V17: Deserialization of Untrusted Data
CVE-2025-40759 is a high-severity deserialization of untrusted data vulnerability in SIMATIC S7-PLCSIM V17 from Siemens, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. Affected SIMATIC S7-PLCSIM V17 versions: all versions. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.22% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update SIMATIC STEP 7 V17 to V17 Update 9 or a later version.
- Update SIMATIC STEP 7 V18 to V18 Update 6 or a later version.
- Update SIMATIC STEP 7 V19 to V19 Update 4 or a later version.
- Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.
Affected products and versions
Version data comes from the organisation that assigned the CVE; 8 further products are omitted here. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- RequiredA user must take an action such as opening a file or link.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H. Scored by CNA (siemens.com).
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 8.5 | High | CNA (siemens.com) |
| CVSS 3.1 | 7.8 | High | CNA (siemens.com) |
Official description
A vulnerability has been identified in SIMATIC S7-PLCSIM V17 (All versions), SIMATIC STEP 7 V17 (All versions < V17 Update 9), SIMATIC STEP 7 V18 (All versions < V18 Update 6), SIMATIC STEP 7 V19 (All versions < V19 Update 4), SIMATIC STEP 7 V20 (All versions < V20 Update 4), SIMATIC WinCC V17 (All versions < V17 Update 9), SIMATIC WinCC V18 (All versions < V18 Update 6), SIMATIC WinCC V19 (All versions < V19 Update 4), SIMATIC WinCC V20 (All versions < V20 Update 4), SIMOCODE ES V17 (All versions), SIMOCODE ES V18 (All versions), SIMOCODE ES V19 (All versions), SIMOCODE ES V20 (All versions), SIMOTION SCOUT TIA V5.4 (All versions), SIMOTION SCOUT TIA V5.5 (All versions), SIMOTION SCOUT TIA V5.6 (All versions < V5.6 SP1 HF7), SIMOTION SCOUT TIA V5.7 (All versions), SINAMICS Startdrive V17 (All versions), SINAMICS Startdrive V18 (All versions), SINAMICS Startdrive V19 (All versions), SINAMICS Startdrive V20 (All versions), SIRIUS Safety ES V17 (TIA Portal) (All versions), SIRIUS Safety ES V18 (TIA Portal) (All versions), SIRIUS Safety ES V19 (TIA Portal) (All versions), SIRIUS Safety ES V20 (TIA Portal) (All versions), SIRIUS Soft Starter ES V17 (TIA Portal) (All versions), SIRIUS Soft Starter ES V18 (TIA Portal) (All versions), SIRIUS Soft Starter ES V19 (TIA Portal) (All versions), SIRIUS Soft Starter ES V20 (TIA Portal) (All versions), TIA Portal Cloud V17 (All versions < V6.0.0.0), TIA Portal Cloud V18 (All versions < V6.3.0.2), TIA Portal Cloud V19 (All versions < V5.2.1.1), TIA Portal Cloud V20 (All versions < V5.2.2.2). Affected products do not properly sanitize stored security properties when parsing project files. This could allow an attacker to cause a type confusion and execute arbitrary code within the affected application.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Deserialization of Untrusted Data
The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.
How developers prevent this class of flaw
- If available, use the signing/sealing features of the programming language to assure that deserialized data has not been tainted. For example, a hash-based message authentication code (HMAC) could be used to ensure that data has not been modified.
- When deserializing data, populate a new object rather than just deserializing. The result is that the data flows through safe input validation and that the functions are safe.
- Explicitly define a final object() to prevent deserialization.
More Deserialization of Untrusted Data vulnerabilities (CWE-502)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Other references
Other vulnerabilities in SIMATIC S7-PLCSIM V17
- 8.2 High severity
- 7.3 High severity
- 7.8 High severity
- 7.3 High severity
Recent Deserialization of Untrusted Data vulnerabilities
- 7.2 High severity
- 9.8 Critical severity
- 7.8 High severity
- 9.8 Critical severity
- 8.4 High severity
- 7.2 High severity
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