# CVE-2026-15105: davenardella snap7 ReadVar Request s7_server.cpp PerformFunctionRead out-of-bounds write

> An out-of-bounds write in snap7's ReadVar handler allows local network attackers to execute code or cause denial of service.

- **Severity:** Medium 5.3 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 8 Jul 2026
- **Updated:** 1 Aug 2026
- **Also known as:** GHSA-x9cg-5m94-27cv, UBUNTU-CVE-2026-15105

## What is CVE-2026-15105?

CVE-2026-15105 is a medium-severity memory corruption vulnerability in davenardella snap7, published on 8 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official 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.

Weakness: CWE-787 (Out-of-bounds Write), CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2026-15105?


## How do I fix CVE-2026-15105?

No fix has been published for CVE-2026-15105 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-15105 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-15105 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-15105 and fix it if it is affected.

What it is: CVE-2026-15105 is a medium-severity memory corruption vulnerability in davenardella snap7, published on 8 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-15105 exists.

Affected product: davenardella snap7. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-15105/ (Markdown: https://insights.sbomify.com/CVE-2026-15105/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-15105
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-15105
- OSV: https://osv.dev/vulnerability/CVE-2026-15105

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-15105/
Summaries are generated and may contain mistakes; the official description above is the record.