# CVE-2023-40891: Memory corruption in n/a

> A stack overflow in the Tenda AC8 router allows attackers to execute arbitrary code or cause a denial of service via the firewall configuration endpoint.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 24 Aug 2023
- **Updated:** 3 Oct 2024
- **Also known as:** GHSA-5j44-8wpg-fpc7

## What is CVE-2023-40891?

CVE-2023-40891 is a critical memory corruption vulnerability in Tenda Ac8 Firmware, published on 24 Aug 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Tenda AC8 v4 US_AC8V4.0si_V16.03.34.06_cn was discovered to contain a stack overflow via parameter firewallEn at /goform/SetFirewallCfg.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2023-40891?

It affects 1 product.


Products: Tenda Ac8 Firmware.

## How do I fix CVE-2023-40891?

No fix has been published for CVE-2023-40891 yet. Limit exposure of the affected software until one is available.

## Is CVE-2023-40891 being exploited?

There is no known exploitation of CVE-2023-40891 in the wild and no public exploit code.

## Other vulnerabilities in Tenda Ac8 Firmware

- [CVE-2025-29100](https://insights.sbomify.com/CVE-2025-29100/): Memory corruption in n/a (critical 9.8)
- [CVE-2025-25663](https://insights.sbomify.com/CVE-2025-25663/): Memory corruption in n/a (critical 9.8)
- [CVE-2025-25664](https://insights.sbomify.com/CVE-2025-25664/): Memory corruption in n/a (critical 9.8)
- [CVE-2025-25667](https://insights.sbomify.com/CVE-2025-25667/): Memory corruption in n/a (critical 9.8)
- [CVE-2025-25668](https://insights.sbomify.com/CVE-2025-25668/): Memory corruption in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-40891 and fix it if it is affected.

What it is: CVE-2023-40891 is a critical memory corruption vulnerability in Tenda Ac8 Firmware, published on 24 Aug 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2023-40891 in the wild and no public exploit code.

Affected product: Tenda Ac8 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-2023-40891/ (Markdown: https://insights.sbomify.com/CVE-2023-40891/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-40891
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-40891
- OSV: https://osv.dev/vulnerability/CVE-2023-40891

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-40891/
Summaries are generated and may contain mistakes; the official description above is the record.