← Vulnerability feed

Vulnerability record · CVE-2026-11826 · published 18 July 2026

CVE-2026-11826: Heap-based buffer overflow vulnerability

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.

8.7 CVSS 4.0 High EPSS 0.75% · top 46.9% CWE-122 · Heap-based buffer overflow Deferred
8.7CVSS 4.0 base score
0.75%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
4References
23 Jul 2026Last modified by NVD

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.

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

References

LinkTags
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

Track CVE-2026-11826 inside VULONE

Watch it alongside the ransomware crews, C2 infrastructure and forum chatter that reference it, query it through the API and pull it into your SIEM over TAXII.

Start free Open in platform

Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.3CVE-2026-94127F5 big-ip access policy manager heap-based buffer overflow vulnerabilityWhen a BIG-IP APM access policy and an OAuth profile are configured on a virtual server, specific malicious traffic can lead to remote code execution…KEVEPSS 2.2%9.8CVE-2025-25249Fortinet FortiOS and FortiSwitchManager heap buffer overflow via crafted packetsA heap-based buffer overflow (CWE-122/CWE-787) in Fortinet FortiOS 6.4 through 7.6.3 and FortiSwitchManager 7.0 through 7.2.6 lets an unauthenticated…KEVEPSS 3.9%analysed7.8CVE-2026-85880Windows ALPC heap buffer overflow allows local privilege escalationA heap-based buffer overflow in the Windows ALPC subsystem, combined with use of an uninitialized resource, lets an attacker with existing local acce…KEVEPSS 3.6%analysed7.8CVE-2026-53362Linux kernel IPv6 UDP paged allocation out-of-bounds write__ip6_append_data() in the Linux kernel mis-accounts fraggap on the paged-allocation path, leaving the linear skb area undersized while pagedlen is o…KEVEPSS 0.71%analysed7.8CVE-2026-56155Microsoft AD FS access control flaw allows local privilege elevationActive Directory Federation Services (AD FS) on multiple Windows client and server versions has insufficient granularity in its access control, letti…KEVEPSS 0.35%analysed8.8CVE-2009-3459Adobe Reader and Acrobat heap buffer overflow via crafted PDFAdobe Reader and Acrobat 7.x before 7.1.4, 8.x before 8.1.7, and 9.x before 9.2 contain a heap-based buffer overflow (CWE-122) triggered by a crafted…KEVEPSS 87%analysed7.8CVE-2026-33825Microsoft Defender Antimalware Platform access control flaw allows local privilege escalationMicrosoft Defender Antimalware Platform has insufficient granularity of access control (CWE-1220), letting an authorized local attacker elevate privi…KEVEPSS 0.40%analysed9.8CVE-2025-31201Apple OS Pointer Authentication bypass via arbitrary read/writeApple removed vulnerable code that allowed an attacker holding arbitrary read and write capability to bypass Pointer Authentication across iOS, iPadO…KEVEPSS 14%analysed

Source: NIST National Vulnerability Database (record CVE-2026-11826), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.