---
cve: "CVE-2026-11826"
severity: "HIGH"
cvss: 8.7
epss: "42%"
vendor: "openplcproject"
kev: false
exploited: false
published: "2026-07-18 14:17:11"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-10T05:42:24+02:00"
---

# CVE-2026-11826

> 8.7 HIGH · 🧪 PoC

## Beschreibung

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-Vektor

```
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
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Gering | warn |
| UI Interaktion | Keine | bad |

## Referenzen

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

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-11826) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_