CVE-2026-11826

OpenPLC_v3 contains a heap-based buffer overflow in the getData() function in webserver/core/modbus_master.cpp. getData() reads characters between two delimiters into a caller-supplied buffer with no size parameter and no bounds check. In parseConfig() the function is invoked with the 100-byte heap-allocated MB_device.dev_name field. 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). A 200-byte payload writes 100 bytes past the allocation. The result is heap corruption leading to runtime crash and denial of service of the PLC process control loop, with attacker-controlled overwrite of adjacent configuration fields. The upstream repository was archived on 2026-04-04 and no fix is expected; the vendor has confirmed the issue does not affect OpenPLC Runtime v4.

CVSS v3 8.8 HIGH

8.8^/10

CVSS v3 : HIGH

Vector :

Exploitability : 2.8 / Impact : 5.9

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required LOW

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://gist.github.com/Shukhrat-03/5cf1825b72e485ef98a32958dfbc611a#security-vulnerability-report
https://github.com/thiagoralves/OpenPLC_v3
https://github.com/thiagoralves/OpenPLC_v3/commit/b4702061dc14d1024856f71b4543298d77007b88
https://www.vulncheck.com/advisories/openplc-v3-heap-based-buffer-overflow-in-modbus-master-getdata

Configurations

No configuration.

History

18 Jul 2026, 14:17

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-07-18 14:17

Updated : 2026-07-23 15:24

NVD link : CVE-2026-11826

Mitre link : CVE-2026-11826

CVE.ORG link : CVE-2026-11826

JSON object : View

Products Affected

No product.

CWE

CWE-122

Heap-based Buffer Overflow

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