ICS/OT impact; affects Siemens SIMATIC ET 200 family across manufacturing; could disrupt plant operations.
CVE-2025-40944
ICS DoS on SIMATIC ET 200 devices via S7 Disconnect handling flaw.
Is CVE-2025-40944 being exploited?
Not confirmed. CVE-2025-40944 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.44% probability of exploitation in the next 30 days.
How severe is CVE-2025-40944?
CVE-2025-40944 is rated High with a CVSS score of 8.7. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2025-40944?
Not known from our data. No patch reference has been recorded for CVE-2025-40944, which is not the same as no patch existing — a fix may have shipped without a tagged reference, or after this record was written. The vendor advisory is the only authority on whether a fix exists, and mitigations may be available regardless.
What does CVE-2025-40944 affect?
CVE-2025-40944 affects SIMATIC ET 200AL IM 157-1 PN (6ES7157-1AB00-0AB0), SIMATIC ET 200MP IM 155-5 PN HF (6ES7155-5AA00-0AC0), SIMATIC ET 200SP IM 155-6 MF HF (6ES7155-6MU00-0CN0), SIMATIC ET 200SP IM 155-6 PN HA (incl. SIPLUS variants) (All versions < V1.3), and 6 further products or versions. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2025-40944?
Patch when available; restrict S7 access; monitor S7 traffic and PLCs.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote DoS: valid S7 Disconnect Request on TCP 102 causes devices to hang; reboot required.
Immediate action required
- affected< *
- affected>= V4.2.0 and < *
- affected< *
- affected>= V4.2.0 and < V4.2.5
- affected< V4.2.2
- affected< V1.3
- affected< V6.0.1
- affected< *
- affected< V6.0.0
- affected>= V4.2.0 and < *
- affected>= V4.2.0 and < *
- affected>= V4.2.0 and < V4.2.5
- affected>= V4.2.0 and < V4.2.5
- affected>= V4.2.0 and < V4.2.5
- affected< V6.0.0
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.