# CVE-2021-47741: ZBL EPON ONU Broadband Router V100R001 Privilege Escalation via Configuration Endpoint

> Limited administrative users can escalate privileges by accessing configuration endpoints to disclose the super user password on ZBL EPON ONU Broadband 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`)
- **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:** 31 Dec 2025
- **Updated:** 2 Jan 2026
- **Also known as:** GHSA-chph-r4jm-2932

## What is CVE-2021-47741?

CVE-2021-47741 is a high-severity vulnerability in Zblchina ZBL EPON ONU Broadband Router, published on 31 Dec 2025. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

ZBL EPON ONU Broadband Router V100R001 contains a privilege escalation vulnerability that allows limited administrative users to elevate access by sending requests to configuration endpoints. Attackers can exploit the vulnerability by accessing the configuration backup or password page to disclose the super user password and gain additional privileged functionalities.

Weakness: CWE-522 (Insufficiently Protected Credentials)

## Which versions are affected by CVE-2021-47741?


## How do I fix CVE-2021-47741?

No fix has been published for CVE-2021-47741 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-47741 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-47741 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-47741 and fix it if it is affected.

What it is: CVE-2021-47741 is a high-severity vulnerability in Zblchina ZBL EPON ONU Broadband Router, published on 31 Dec 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-2021-47741 exists.

Affected product: Zblchina ZBL EPON ONU Broadband Router. 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-2021-47741/ (Markdown: https://insights.sbomify.com/CVE-2021-47741/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-47741
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-47741
- OSV: https://osv.dev/vulnerability/CVE-2021-47741

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-47741/
Summaries are generated and may contain mistakes; the official description above is the record.