Is CVE-2026-51218 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-51218 being exploited in the wild.

How severe is CVE-2026-51218?

Informational severity, with a CVSS score of 7.5, published 29 June 2026.

Is there a fix for CVE-2026-51218?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-51218 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-51218?

Check whether you run Snap7 Project Snap7 at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-51218: Snap7 heap buffer overflow in TS7Worker::PerformFunctionWrite

CVE-2026-51218 · Severity: info · CVSS 7.5 · Published 2026-06-29

Snap7 is an open-source communication library used to interface with Siemens S7 PLCs (Programmable Logic Controllers) in industrial environments. A vulnerability in the library's server component allows a remote attacker to crash the service by sending a specially crafted network packet. This could lead to a denial-of-service (DoS) condition, disrupting industrial monitoring or control operations that rely on this library.

Technologies: Snap7 Project Snap7. Vendors: Snap7 Project.

Quick answers

Is CVE-2026-51218 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-51218 being exploited in the wild.
How severe is CVE-2026-51218?: Informational severity, with a CVSS score of 7.5, published 29 June 2026.
Which products and versions are affected?: Snap7 Project Snap7 1.4.3.
Is there a fix for CVE-2026-51218?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-51218 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-51218?: Check whether you run Snap7 Project Snap7 at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A heap buffer overflow exists in Snap7 v1.4.3 within the `TS7Worker::PerformFunctionWrite()` function located in `src/core/s7_server.cpp`. The vulnerability is triggered during the parsing of malformed S7 `WriteVar` requests. An attacker can exploit this by sending a specially crafted TCP packet to a Snap7 server instance, leading to an out-of-bounds read/write on the heap. This results in an immediate crash of the worker thread or the entire server process (Denial of Service). The issue is reproducible over the network without authentication. As of the advisory date, the issue was reported via the project's GitHub repository.

Affected products

Snap7 Project (davenardella) Snap7 1.4.3

Timeline

2026-06-29: advisory: CVE published to NVD dataset
2026-06-29: disclosed: Issue reported on GitHub repository

References

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