Auth bypass in widely deployed PLCs can enable full control/shutdown of industrial processes — high-impact across OT environments and likely to make security news.
CVE-2026-3869
Authentication bypass in PLCs enabling unauthorized full control.
Is CVE-2026-3869 being exploited?
Not confirmed. CVE-2026-3869 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 0.54% probability of exploitation in the next 30 days.
How severe is CVE-2026-3869?
CVE-2026-3869 is rated Critical with a CVSS score of 9.2. 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-2026-3869?
Not known from our data. No patch reference has been recorded for CVE-2026-3869, 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-2026-3869 affect?
CVE-2026-3869 affects Schneider Electric PLCs (SEVD-2026-251-04), Industrial control systems running lower application-level projects on affected PLCs. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-3869?
Isolate affected PLCs, apply vendor mitigations, deploy vendor update when available.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Authentication bypass allows remote unauthorized control of PLCs — remote code/logic manipulation, process disruption, data theft, or DoS.
Immediate action required
- affectedAll versions with an application level below 4.00
- affectedAll versions with an application level below 4.20
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.