# CVE-2021-26637: SiHAS Improper Authentication vulnerability

> Unauthorized users can remotely control SiHAS devices due to missing authentication and permission checks in firmware and apps.

- **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:** 22 Jun 2022
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-4j8v-2qmr-6m8p

## What is CVE-2021-26637?

CVE-2021-26637 is a high-severity missing authorization vulnerability in Shina System Co.,Ltd SiHAS firmware, published on 22 Jun 2022. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

There is no account authentication and permission check logic in the firmware and existing apps of SiHAS's SGW-300, ACM-300, GCM-300, so unauthorized users can remotely control the device.

Weakness: CWE-862 (Missing Authorization), CWE-306 (Missing Authentication for Critical Functionality), CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2021-26637?

It affects 3 products.


Products: Shinasys Sihas Acm-300 Firmware, Shinasys Sihas Gcm-300 Firmware, Shinasys Sihas Sgw-300 Firmware.

## How do I fix CVE-2021-26637?

No fix has been published for CVE-2021-26637 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-26637 being exploited?

There is no known exploitation of CVE-2021-26637 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-26637 and fix it if it is affected.

What it is: CVE-2021-26637 is a high-severity missing authorization vulnerability in Shina System Co.,Ltd SiHAS firmware, published on 22 Jun 2022. 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-2021-26637 in the wild and no public exploit code.

Affected product: Shina System Co.,Ltd SiHAS 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-2021-26637/ (Markdown: https://insights.sbomify.com/CVE-2021-26637/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-26637
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-26637
- OSV: https://osv.dev/vulnerability/CVE-2021-26637

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-26637/
Summaries are generated and may contain mistakes; the official description above is the record.