# CVE-2021-20861: Auth bypass in ELECOM LAN routers

> Authenticated network-adjacent attackers can bypass access restrictions to reach the management interface of ELECOM LAN routers.

- **Severity:** High 8.8 (`CVSS:3.1/AV:A/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:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 1 Dec 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-cjfc-g68m-vj47

## What is CVE-2021-20861?

CVE-2021-20861 is a high-severity authentication bypass vulnerability in ELECOM LAN routers, published on 1 Dec 2021. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Improper access control vulnerability in ELECOM LAN routers (WRC-1167GST2 firmware v1.25 and prior, WRC-1167GST2A firmware v1.25 and prior, WRC-1167GST2H firmware v1.25 and prior, WRC-2533GS2-B firmware v1.52 and prior, WRC-2533GS2-W firmware v1.52 and prior, WRC-1750GS firmware v1.03 and prior, WRC-1750GSV firmware v2.11 and prior, WRC-1900GST firmware v1.03 and prior, WRC-2533GST firmware v1.03 and prior, WRC-2533GSTA firmware v1.03 and prior, WRC-2533GST2 firmware v1.25 and prior, WRC-2533GST2SP firmware v1.25 and prior, WRC-2533GST2-G firmware v1.25 and prior, and EDWRC-2533GST2 firmware v1.25 and prior) allows a network-adjacent authenticated attacker to bypass access restriction and to access the management screen of the product via unspecified vectors.

## Which versions are affected by CVE-2021-20861?

It affects 14 products.


Products: Elecom Edwrc-2533gst2 Firmware, Elecom Wrc-1167gst2 Firmware, Elecom Wrc-1167gst2a Firmware, Elecom Wrc-1167gst2h Firmware, Elecom Wrc-1750gs Firmware, Elecom Wrc-1750gsv Firmware, Elecom Wrc-1900gst Firmware, Elecom Wrc-2533gs2-B Firmware, Elecom Wrc-2533gs2-W Firmware, Elecom Wrc-2533gst2-G Firmware, Elecom Wrc-2533gst2 Firmware, Elecom Wrc-2533gst2sp Firmware, Elecom Wrc-2533gst Firmware, Elecom Wrc-2533gsta Firmware.

## How do I fix CVE-2021-20861?

No fix has been published for CVE-2021-20861 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-20861 being exploited?

There is no known exploitation of CVE-2021-20861 in the wild and no public exploit code.

## Other vulnerabilities in ELECOM LAN routers

- [CVE-2022-25915](https://insights.sbomify.com/CVE-2022-25915/): Auth bypass in ELECOM LAN routers (high 8.8)
- [CVE-2021-20860](https://insights.sbomify.com/CVE-2021-20860/): Cross-site request forgery in ELECOM LAN routers (high 8.8)
- [CVE-2021-20864](https://insights.sbomify.com/CVE-2021-20864/): Auth bypass in ELECOM routers (high 8.8)
- [CVE-2021-20859](https://insights.sbomify.com/CVE-2021-20859/): Command injection in ELECOM LAN routers (high 8.0)
- [CVE-2021-20863](https://insights.sbomify.com/CVE-2021-20863/): Command injection in ELECOM routers (high 8.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-20861 and fix it if it is affected.

What it is: CVE-2021-20861 is a high-severity authentication bypass vulnerability in ELECOM LAN routers, published on 1 Dec 2021. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-20861 in the wild and no public exploit code.

Affected product: ELECOM LAN routers. 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-2021-20861/ (Markdown: https://insights.sbomify.com/CVE-2021-20861/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-20861
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-20861
- OSV: https://osv.dev/vulnerability/CVE-2021-20861

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-20861/
Summaries are generated and may contain mistakes; the official description above is the record.