# CVE-2021-21726: Denial of service in <ZXONE 9700 , ZXONE 8700, ZXONE 19700>

> High-privilege attackers can cause denial of service in ZTE optical network devices by repeatedly inputting illegal parameters into the diagnostic interface.

- **Severity:** Low 2.3 (`CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 12 Mar 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-gp9j-h6cw-964w

## What is CVE-2021-21726?

CVE-2021-21726 is a low-severity denial of service vulnerability in <ZXONE 9700 , ZXONE 8700, ZXONE 19700>, published on 12 Mar 2021. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Some ZTE products have an input verification vulnerability in the diagnostic function interface. Due to insufficient verification of some parameters input by users, an attacker with high privileges can cause process exception by repeatedly inputting illegal parameters. This affects:<ZXONE 9700 , ZXONE 8700, ZXONE 19700><V1.40.021.021CP049, V1.0P02B219_@NCPM-RELEASE_2.40R1-20200914.set>

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2021-21726?

It affects 3 products.


Products: Zte Zxone 19700 Firmware, Zte Zxone 8700 Firmware, Zte Zxone 9700 Firmware.

## How do I fix CVE-2021-21726?

No fix has been published for CVE-2021-21726 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-21726 being exploited?

There is no known exploitation of CVE-2021-21726 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-21726 and fix it if it is affected.

What it is: CVE-2021-21726 is a low-severity denial of service vulnerability in <ZXONE 9700 , ZXONE 8700, ZXONE 19700>, published on 12 Mar 2021. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-21726 in the wild and no public exploit code.

Affected product: <ZXONE 9700 , ZXONE 8700, ZXONE 19700>. 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-2021-21726/ (Markdown: https://insights.sbomify.com/CVE-2021-21726/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-21726
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-21726
- OSV: https://osv.dev/vulnerability/CVE-2021-21726

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From sbomify Insights: https://insights.sbomify.com/CVE-2021-21726/
Summaries are generated and may contain mistakes; the official description above is the record.