CVE-2026-11826
Authenticated buffer overflow in OpenPLC v3 /modbus endpoint allows config overwrite and DoS.
Is CVE-2026-11826 being exploited?
Not confirmed. CVE-2026-11826 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 0.75% probability of exploitation in the next 30 days.
How severe is CVE-2026-11826?
CVE-2026-11826 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-2026-11826?
Not known from our data. No patch reference has been recorded for CVE-2026-11826, 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-2026-11826 affect?
CVE-2026-11826 affects OpenPLC v3 (modbus_master.cpp getData), Devices running OpenPLC v3, mbconfig.cfg. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-11826?
Restrict web UI access, block /modbus POSTs, isolate devices, migrate to OpenPLC Runtime v4.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Authenticated attacker can send crafted /modbus POST to overflow dev_name, overwrite adjacent config fields and crash the PLC control loop (DoS) and alter protocol/address/port fields.
Immediate action required
- affected<= b470206
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.