CVE-2026-11826: OpenPLC_v3 0 through b470206

Affected technology

OpenPLC_v3 · 0 through b470206
openplcproject

Component: Not specified by the source
Function: in, is

Attack conditions (Vendor/CNA, CVSS 4.0): Network (remote) · Low privileges required · No user interaction required

What an attacker can do

An authenticated attacker with access to the OpenPLC web interface can send a crafted HTTP POST to the /modbus endpoint with an oversized device_name value; the value is persisted to mbconfig.cfg and parsed on load, overflowing dev_name and overwriting adjacent struct fields (protocol at offset 108, dev_address at offset 109, ip_port at offset 210). Vendor/CNA’s CVSS 4.0 assessment (base score 8.7/10) rates confidentiality, integrity and availability impact as high.