# CVE-2026-3972: Tenda W3 HTTP setcfm formSetCfm stack-based overflow

> A stack-based buffer overflow in the Tenda W3 router's HTTP handler allows local network attackers to execute arbitrary code.

- **Severity:** High 8.7 (`CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P`)
- **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:** 12 Mar 2026
- **Updated:** 12 Mar 2026
- **Also known as:** GHSA-j4r5-rc95-5xpf

## What is CVE-2026-3972?

CVE-2026-3972 is a high-severity memory corruption vulnerability in Tenda W3, published on 12 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A vulnerability was found in Tenda W3 1.0.0.3(2204). Affected by this issue is the function formSetCfm of the file /goform/setcfm of the component HTTP Handler. The manipulation of the argument funcpara1 results in stack-based buffer overflow. The attack can only be performed from the local network. The exploit has been made public and could be used.

Weakness: CWE-121 (Stack-based Buffer Overflow), CWE-787 (Out-of-bounds Write), CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2026-3972?

It affects 1 product.


Products: Tenda W3 Firmware.

## How do I fix CVE-2026-3972?

No fix has been published for CVE-2026-3972 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-3972 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-3972 exists.

## Other vulnerabilities in Tenda W3

- [CVE-2026-3973](https://insights.sbomify.com/CVE-2026-3973/): Tenda W3 POST Parameter setAutoPing formSetAutoPing stack-based overflow (high 8.7)
- [CVE-2026-3974](https://insights.sbomify.com/CVE-2026-3974/): Tenda W3 HTTP exeCommand formexeCommand stack-based overflow (high 8.7)
- [CVE-2026-3975](https://insights.sbomify.com/CVE-2026-3975/): Tenda W3 POST Parameter WifiMacFilterGet formWifiMacFilterGet stack-based overflow (high 8.7)
- [CVE-2026-3976](https://insights.sbomify.com/CVE-2026-3976/): Tenda W3 POST Parameter WifiMacFilterSet formWifiMacFilterSet stack-based overflow (high 8.7)
- [CVE-2026-4007](https://insights.sbomify.com/CVE-2026-4007/): Tenda W3 POST Parameter wifiSSIDget stack-based overflow (high 8.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-3972 and fix it if it is affected.

What it is: CVE-2026-3972 is a high-severity memory corruption vulnerability in Tenda W3, published on 12 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-3972 exists.

Affected product: Tenda W3. 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-2026-3972/ (Markdown: https://insights.sbomify.com/CVE-2026-3972/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-3972
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-3972
- OSV: https://osv.dev/vulnerability/CVE-2026-3972

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-3972/
Summaries are generated and may contain mistakes; the official description above is the record.