# CVE-2026-5043: Belkin F9K1122 Parameter formSetPassword stack-based overflow

> Remote attackers can exploit a stack-based buffer overflow in the password setting function to execute arbitrary code on Belkin F9K1122 routers.

- **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:** 29 Mar 2026
- **Updated:** 30 Mar 2026
- **Also known as:** GHSA-h95j-mxr9-q69c

## What is CVE-2026-5043?

CVE-2026-5043 is a high-severity memory corruption vulnerability in Belkin F9K1122, published on 29 Mar 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

A weakness has been identified in Belkin F9K1122 1.00.33. The impacted element is the function formSetPassword of the file /goform/formSetPassword of the component Parameter Handler. This manipulation of the argument webpage causes stack-based buffer overflow. Remote exploitation of the attack is possible. The exploit has been made available to the public and could be used for attacks. The vendor was contacted early about this disclosure but did not respond in any way.

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-2026-5043?

It affects 1 product.


Products: Belkin F9k1122 Firmware.

## How do I fix CVE-2026-5043?

No fix has been published for CVE-2026-5043 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-5043 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-5043 exists.

## Other vulnerabilities in Belkin F9K1122

- [CVE-2026-5608](https://insights.sbomify.com/CVE-2026-5608/): Belkin F9K1122 formWlanSetup stack-based overflow (high 8.7)
- [CVE-2026-5042](https://insights.sbomify.com/CVE-2026-5042/): Belkin F9K1122 Parameter formCrossBandSwitch stack-based overflow (high 8.7)
- [CVE-2026-5044](https://insights.sbomify.com/CVE-2026-5044/): Belkin F9K1122 Setting formSetSystemSettings stack-based overflow (high 8.7)
- [CVE-2026-4566](https://insights.sbomify.com/CVE-2026-4566/): Belkin F9K1122 formWISP5G stack-based overflow (high 8.7)
- [CVE-2025-7084](https://insights.sbomify.com/CVE-2025-7084/): Belkin F9K1122 webs formWpsStart stack-based overflow (high 8.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-5043 and fix it if it is affected.

What it is: CVE-2026-5043 is a high-severity memory corruption vulnerability in Belkin F9K1122, published on 29 Mar 2026. 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-2026-5043 exists.

Affected product: Belkin F9K1122. 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-2026-5043/ (Markdown: https://insights.sbomify.com/CVE-2026-5043/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-5043
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-5043
- OSV: https://osv.dev/vulnerability/CVE-2026-5043

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-5043/
Summaries are generated and may contain mistakes; the official description above is the record.