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Vulnerabilities CVE-2026-11826

CVE-2026-11826

High
Open
TLP:CLEAR

OpenPLC_v3 Heap-Based Buffer Overflow in Modbus Master getData()

NVD CVE.org
Critical Infrastructure DDoS

AI Analysis

No AI analysis yet.

Description

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.

Details

CVSS Score
8.7
EPSS Score
0.42%

34.9th percentile

CVSS Vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Confidence
90%
Published
Jul 18, 2026
Last Modified
Jul 28, 2026
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