# CVE-2025-5839: Tenda AC9 POST Request AdvSetLanip fromadvsetlanip buffer overflow

> Remote attackers can trigger a buffer overflow in the Tenda AC9 router via a crafted POST request, potentially leading to code execution or service disruption.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P`)
- **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:** 7 Jun 2025
- **Updated:** 9 Jun 2025
- **Also known as:** GHSA-xpmp-hffj-q43q

## What is CVE-2025-5839?

CVE-2025-5839 is a high-severity memory corruption vulnerability in Tenda Ac9 Firmware, published on 7 Jun 2025. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

A vulnerability, which was classified as critical, has been found in Tenda AC9 15.03.02.13. Affected by this issue is the function fromadvsetlanip of the file /goform/AdvSetLanip of the component POST Request Handler. The manipulation of the argument lanMask leads to buffer overflow. The attack may be launched remotely. The exploit has been disclosed to the public and may be used.

Weakness: CWE-120 (Buffer Copy without Checking Size of Input), CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2025-5839?

It affects 1 product.


Products: Tenda Ac9 Firmware.

## How do I fix CVE-2025-5839?

No fix has been published for CVE-2025-5839 yet. Limit exposure of the affected software until one is available.

## Is CVE-2025-5839 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-5839 exists.

## 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-2025-5839 and fix it if it is affected.

What it is: CVE-2025-5839 is a high-severity memory corruption vulnerability in Tenda Ac9 Firmware, published on 7 Jun 2025. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-5839 exists.

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-2025-5839/ (Markdown: https://insights.sbomify.com/CVE-2025-5839/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-5839
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-5839
- OSV: https://osv.dev/vulnerability/CVE-2025-5839

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-5839/
Summaries are generated and may contain mistakes; the official description above is the record.