# CVE-2020-9307: Denial of service in n/a

> An unauthenticated adjacent attacker can cause an infinite loop on HSR ring ports, breaking network redundancy and disrupting communication.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/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:** 11 Feb 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-gfvh-r99j-x28p

## What is CVE-2020-9307?

CVE-2020-9307 is a medium-severity denial of service vulnerability in n/a, published on 11 Feb 2021. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Hirschmann OS2, RSP, and RSPE devices before HiOS 08.3.00 allow a denial of service. An unauthenticated, adjacent attacker can cause an infinite loop on one of the HSR ring ports of the device. This effectively breaks the redundancy of the HSR ring. If the attacker can perform the same attack on a second device, the ring is broken into two parts (thus disrupting communication between devices in the different parts).

Weakness: CWE-835 (Loop with Unreachable Exit Condition)

## Which versions are affected by CVE-2020-9307?

It affects 1 product.


Products: Belden Hirschmann Hios.

## How do I fix CVE-2020-9307?

No fix has been published for CVE-2020-9307 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-9307 being exploited?

There is no known exploitation of CVE-2020-9307 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2021-27734](https://insights.sbomify.com/CVE-2021-27734/): Auth bypass in n/a (critical 9.8)
- [CVE-2020-6994](https://insights.sbomify.com/CVE-2020-6994/): Memory corruption in HiOS for the following devices RSP, RSPE, RSPS, RSPL, MSP, EES, EES, EESX, GRS, OS, RED (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-9307 and fix it if it is affected.

What it is: CVE-2020-9307 is a medium-severity denial of service vulnerability in n/a, published on 11 Feb 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-2020-9307 in the wild and no public exploit code.

Affected product: n/a. 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-2020-9307/ (Markdown: https://insights.sbomify.com/CVE-2020-9307/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-9307
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-9307
- OSV: https://osv.dev/vulnerability/CVE-2020-9307

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-9307/
Summaries are generated and may contain mistakes; the official description above is the record.