# CVE-2021-33535: WEIDMUELLER: WLAN devices affected by exploitable format string vulnerability

> Authenticated low-privilege users can trigger a format string vulnerability in Weidmüller WLAN devices to achieve remote code execution.

- **Severity:** High 8.8 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 25 Jun 2021
- **Updated:** 17 Sep 2024
- **Also known as:** GHSA-79h3-q6m5-2593

## What is CVE-2021-33535?

CVE-2021-33535 is a high-severity vulnerability in Weidmüller IE-WL(T)-BL-AP-CL-XX, published on 25 Jun 2021. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

In Weidmueller Industrial WLAN devices in multiple versions an exploitable format string vulnerability exists in the iw_console conio_writestr functionality. A specially crafted time server entry can cause an overflow of the time server buffer, resulting in remote code execution. An attacker can send commands while authenticated as a low privilege user to trigger this vulnerability.

Weakness: CWE-134 (Use of Externally-Controlled Format String)

## Which versions are affected by CVE-2021-33535?

It affects 8 products.


Products: Weidmueller Ie-Wl-Bl-Ap-Cl-Eu Firmware, Weidmueller Ie-Wl-Bl-Ap-Cl-Us Firmware, Weidmueller Ie-Wl-Vl-Ap-Br-Cl-Eu Firmware, Weidmueller Ie-Wl-Vl-Ap-Br-Cl-Us Firmware, Weidmueller Ie-Wlt-Bl-Ap-Cl-Eu Firmware, Weidmueller Ie-Wlt-Bl-Ap-Cl-Us Firmware, Weidmueller Ie-Wlt-Vl-Ap-Br-Cl-Eu Firmware, Weidmueller Ie-Wlt-Vl-Ap-Br-Cl-Us Firmware.

## How do I fix CVE-2021-33535?

No fix has been published for CVE-2021-33535 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-33535 being exploited?

There is no known exploitation of CVE-2021-33535 in the wild and no public exploit code.

## Other vulnerabilities in Weidmüller IE-WL(T)-BL-AP-CL-XX

- [CVE-2021-33528](https://insights.sbomify.com/CVE-2021-33528/): WEIDMUELLER: WLAN devices affected by privilege escalation vulnerability (high 8.8)
- [CVE-2021-33530](https://insights.sbomify.com/CVE-2021-33530/): WEIDMUELLER: WLAN devices affected by OS Command Injection vulnerability (high 8.8)
- [CVE-2021-33531](https://insights.sbomify.com/CVE-2021-33531/): WEIDMUELLER: WLAN devices affected by Hard-coded Credentials vulnerability (high 8.8)
- [CVE-2021-33532](https://insights.sbomify.com/CVE-2021-33532/): WEIDMUELLER: WLAN devices affected by OS Command Injection vulnerability (high 8.8)
- [CVE-2021-33533](https://insights.sbomify.com/CVE-2021-33533/): WEIDMUELLER: WLAN devices affected by OS Command Injection vulnerability (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-33535 and fix it if it is affected.

What it is: CVE-2021-33535 is a high-severity vulnerability in Weidmüller IE-WL(T)-BL-AP-CL-XX, published on 25 Jun 2021. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-33535 in the wild and no public exploit code.

Affected product: Weidmüller IE-WL(T)-BL-AP-CL-XX. 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-2021-33535/ (Markdown: https://insights.sbomify.com/CVE-2021-33535/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-33535
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-33535
- OSV: https://osv.dev/vulnerability/CVE-2021-33535

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From sbomify Insights: https://insights.sbomify.com/CVE-2021-33535/
Summaries are generated and may contain mistakes; the official description above is the record.