# CVE-2021-34740: Cisco Aironet Access Points WLAN Control Protocol Packet Buffer Leak Denial of Service Vulnerability


- **Severity:** High 7.4 (`CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Fix available:** No
- **Published:** 23 Sep 2021
- **Updated:** 7 Nov 2024
- **Also known as:** GHSA-8j6f-39hh-f4v6

## What is CVE-2021-34740?

CVE-2021-34740 is a high-severity vulnerability in Cisco Aironet Access Point Software, published on 23 Sep 2021. 

### Official description

A vulnerability in the WLAN Control Protocol (WCP) implementation for Cisco Aironet Access Point (AP) software could allow an unauthenticated, adjacent attacker to cause a reload of an affected device, resulting in a denial of service (DoS) condition. This vulnerability is due to incorrect error handling when an affected device receives an unexpected 802.11 frame. An attacker could exploit this vulnerability by sending certain 802.11 frames over the wireless network to an interface on an affected AP. A successful exploit could allow the attacker to cause a packet buffer leak. This could eventually result in buffer allocation failures, which would trigger a reload of the affected device.

Weakness: CWE-401 (Missing Release of Memory after Effective Lifetime)

## Which versions are affected by CVE-2021-34740?

It affects 1 product.


Products: Cisco Aironet Access Point Software.

## How do I fix CVE-2021-34740?

No fix has been published for CVE-2021-34740 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-34740 being exploited?

There is no known exploitation of CVE-2021-34740 in the wild and no public exploit code.

## Other vulnerabilities in Cisco Aironet Access Point Software

- [CVE-2017-3831](https://insights.sbomify.com/CVE-2017-3831/): Auth bypass in Cisco Mobility Express 1800 Access Point Series (critical 9.8)
- [CVE-2022-20622](https://insights.sbomify.com/CVE-2022-20622/): Cisco Embedded Wireless Controller with Catalyst Access Points IP Flood Denial of Service Vulnerability (high 8.6)
- [CVE-2018-0234](https://insights.sbomify.com/CVE-2018-0234/): Denial of service in Cisco Aironet 1810, 1830, and 1850 Series Access Points (high 8.6)
- [CVE-2016-1419](https://insights.sbomify.com/CVE-2016-1419/): Denial of service in n/a (high 8.1)
- [CVE-2016-6362](https://insights.sbomify.com/CVE-2016-6362/): Privilege escalation in n/a (high 7.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-34740 and fix it if it is affected.

What it is: CVE-2021-34740 is a high-severity vulnerability in Cisco Aironet Access Point Software, published on 23 Sep 2021. 
Exploitation: There is no known exploitation of CVE-2021-34740 in the wild and no public exploit code.

Affected product: Cisco Aironet Access Point Software. 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-2021-34740/ (Markdown: https://insights.sbomify.com/CVE-2021-34740/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-34740
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-34740
- OSV: https://osv.dev/vulnerability/CVE-2021-34740

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-34740/
Summaries are generated and may contain mistakes; the official description above is the record.