---
id: CVE-2026-111280
title: 'snap7 through 1.4.3 Out-of-Bounds Write via TSnap7MicroClient::opReadArea'
summary: >-
  snap7 through 1.4.3 contains an out-of-bounds write vulnerability in
  TSnap7MicroClient::opReadArea() that allows malicious S7 peers to overflow
  client buffers via an unchecked DataLength field. Rogue or impersonated PLCs
  can return craft…
severity: high
cvss: 7.4
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:H'
cvssSource: cna
cwe:
  - CWE-787
vendor: davenardella
product: snap7
affected:
  - snap7 <= 1.4.3
published: '2026-10-15'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T21:43:24.650Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-111280'
references:
  - url: 'https://github.com/davenardella/snap7/issues/31'
  - url: >-
      https://github.com/davenardella/snap7/blob/30f37da3114024a71ba93f7fd855c680b97a406f/src/core/s7_micro_client.cpp#L136-L150
  - url: 'https://github.com/davenardella/snap7'
  - url: >-
      https://www.vulncheck.com/advisories/snap7-through-1.4.3-out-of-bounds-write-via-tsnap7microclient-opreadarea
    label: >-
      VulnCheck Advisory: snap7 through 1.4.3 Out-of-Bounds Write via
      TSnap7MicroClient::opReadArea
tags:
  - cve.org
ingestedAt: '2026-10-15T22:48:25.449Z'
---

## Overview

snap7 through 1.4.3 contains an out-of-bounds write vulnerability in TSnap7MicroClient::opReadArea() that allows malicious S7 peers to overflow client buffers via an unchecked DataLength field. Rogue or impersonated PLCs can return crafted ReadVar responses causing memcpy of up to 65535 bytes into caller buffers, crashing SCADA, HMI, or gateway processes and corrupting memory.

## Affected

- `snap7 <= 1.4.3`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.