# CVE-2026-51218

> As of 2026-06-30, CVE-2026-51218 is a MEDIUM-severity vulnerability, CVSS v3.1 6.5. Threadlinqs Intelligence links 1 tracked threat campaign to CVE-2026-51218, most recently “AI-Powered Attacks Targeting Siemens S7 Series PLCs in U.S. Critical Infrastructure”.

**Last updated:** 2026-06-30

## What is CVE-2026-51218?

A heap buffer overflow in the TS7Worker::PerformFunctionWrite() function (/core/s7_server.cpp) of snap7 v1.4.3 allows attackers to cause a Denial of Service (DoS) via a crafted packet.

The record classifies CVE-2026-51218 under weakness class [CWE-122](https://cwe.mitre.org/data/definitions/122.html). Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs a user to take an action first, and has high impact on availability. The identifier was first published 76 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 6.5 — MEDIUM (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H`)
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 3.3/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-06-29, last modified 2026-06-30

## Is CVE-2026-51218 being exploited?

It currently carries a trending score of 30 in the Threadlinqs vulnerability feed.

## Affected products and versions

No affected-product or package list has been recorded for CVE-2026-51218 in the tracked sources. The vendor advisory and the references below are the authoritative statement of what is affected.

## How to fix CVE-2026-51218

No vendor patch reference has been recorded for CVE-2026-51218 in the tracked sources. Follow the references below for a fix, and treat any affected deployment as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-51218

1 tracked threat in the Threadlinqs corpus references CVE-2026-51218, either in the campaign’s CVE list or as an indicator on the campaign record.

- [AI-Powered Attacks Targeting Siemens S7 Series PLCs in U.S. Critical Infrastructure](https://intel.threadlinqs.com/threat/TL-2026-2076) — CRITICAL · 2026-08-19

## Sources

Enriched from CVE.org. Last verified by Threadlinqs on 2026-07-01.

**Other references**

- [github.com](https://github.com/davenardella/snap7)
- [github.com (14)](https://github.com/davenardella/snap7/issues/14)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-51218
Full detection coverage and IOCs for threats exploiting CVE-2026-51218 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp