# CVE-2021-1524: Cisco Meeting Server API Denial of Service Vulnerability

> An authenticated remote attacker can cause a denial of service by sending malicious API requests, disconnecting all call participants.

- **Severity:** Medium 4.3 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L`)
- **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:** 16 Jun 2021
- **Updated:** 7 Nov 2024
- **Also known as:** GHSA-cqqf-7hc8-ww46

## What is CVE-2021-1524?

CVE-2021-1524 is a medium-severity denial of service vulnerability in Cisco Meeting Server, published on 16 Jun 2021. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

A vulnerability in the API of Cisco Meeting Server could allow an authenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability exists because requests that are sent to the API are not properly validated. An attacker could exploit this vulnerability by sending a malicious request to the API. A successful exploit could allow the attacker to cause all participants on a call to be disconnected, resulting in a DoS condition.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2021-1524?

It affects 1 product.


Products: Cisco Meeting Server.

## How do I fix CVE-2021-1524?

No fix has been published for CVE-2021-1524 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-1524 being exploited?

There is no known exploitation of CVE-2021-1524 in the wild and no public exploit code.

## Other vulnerabilities in Cisco Meeting Server

- [CVE-2016-6448](https://insights.sbomify.com/CVE-2016-6448/): Memory corruption in Cisco Meeting Server before 2.0.3 and Acano Server before 1.9.5 (critical 9.8)
- [CVE-2017-12249](https://insights.sbomify.com/CVE-2017-12249/): Misconfiguration in Cisco Meeting Server (critical 9.1)
- [CVE-2016-6445](https://insights.sbomify.com/CVE-2016-6445/): Auth bypass in Cisco Meeting Server (CMS) before 2.0.6 and Acano Server before 1.8.18 and 1.9.x before 1.9.6 (critical 9.1)
- [CVE-2018-0439](https://insights.sbomify.com/CVE-2018-0439/): Cisco Meeting Server Cross-Site Request Forgery Vulnerability (high 8.8)
- [CVE-2016-6444](https://insights.sbomify.com/CVE-2016-6444/): Cross-site request forgery in Cisco Meeting Server 1.8, 1.9, 2.0 (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-1524 and fix it if it is affected.

What it is: CVE-2021-1524 is a medium-severity denial of service vulnerability in Cisco Meeting Server, published on 16 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-2021-1524 in the wild and no public exploit code.

Affected product: Cisco Meeting Server. 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-2021-1524/ (Markdown: https://insights.sbomify.com/CVE-2021-1524/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-1524
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-1524
- OSV: https://osv.dev/vulnerability/CVE-2021-1524

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-1524/
Summaries are generated and may contain mistakes; the official description above is the record.