# CVE-2021-42659: Memory corruption in n/a

> A buffer overflow in the Tenda router web server causes a crash when processing long virtual service parameters, leading to denial of service.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **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:** 24 May 2022
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-mf8h-g57h-xqhr

## What is CVE-2021-42659?

CVE-2021-42659 is a medium-severity memory corruption vulnerability in Tenda Ac9 Firmware, published on 24 May 2022. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

There is a buffer overflow vulnerability in the Web server httpd of the router in Tenda router devices such as Tenda AC9 V1.0 V15.03.02.19(6318) and Tenda AC9 V3.0 V15.03.06.42_multi. When setting the virtual service, the httpd program will crash and exit when the super-long list parameter occurs.

Weakness: CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2021-42659?

It affects 1 product.


Products: Tenda Ac9 Firmware.

## How do I fix CVE-2021-42659?

No fix has been published for CVE-2021-42659 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-42659 being exploited?

There is no known exploitation of CVE-2021-42659 in the wild and no public exploit code.

## Other vulnerabilities in Tenda Ac9 Firmware

- [CVE-2025-45042](https://insights.sbomify.com/CVE-2025-45042/): Command injection in n/a (critical 9.8)
- [CVE-2025-44872](https://insights.sbomify.com/CVE-2025-44872/): Command injection in n/a (critical 9.8)
- [CVE-2025-44877](https://insights.sbomify.com/CVE-2025-44877/): Command injection in n/a (critical 9.8)
- [CVE-2025-45427](https://insights.sbomify.com/CVE-2025-45427/): Memory corruption in n/a (critical 9.8)
- [CVE-2025-45428](https://insights.sbomify.com/CVE-2025-45428/): Memory corruption in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-42659 and fix it if it is affected.

What it is: CVE-2021-42659 is a medium-severity memory corruption vulnerability in Tenda Ac9 Firmware, published on 24 May 2022. 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-2021-42659 in the wild and no public exploit code.

Affected product: Tenda Ac9 Firmware. 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-2021-42659/ (Markdown: https://insights.sbomify.com/CVE-2021-42659/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-42659
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-42659
- OSV: https://osv.dev/vulnerability/CVE-2021-42659

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-42659/
Summaries are generated and may contain mistakes; the official description above is the record.