# CVE-2021-27420: GE UR family input validation

> An attacker can cause the GE UR relay web server to become unresponsive by sending unsupported HTTP verbs, temporarily blocking web access.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 23 Mar 2022
- **Updated:** 16 Apr 2025
- **Also known as:** GHSA-vw3w-wmxj-qpxw

## What is CVE-2021-27420?

CVE-2021-27420 is a medium-severity denial of service vulnerability in GE UR family, published on 23 Mar 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

GE UR firmware versions prior to version 8.1x web server task does not properly handle receipt of unsupported HTTP verbs, resulting in the web server becoming temporarily unresponsive after receiving a series of unsupported HTTP requests. When unresponsive, the web server is inaccessible. By itself, this is not particularly significant as the relay remains effective in all other functionality and communication channels.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2021-27420?

It affects 19 products.


Products: Ge Multilin B30 Firmware, Ge Multilin B90 Firmware, Ge Multilin C30 Firmware, Ge Multilin C60 Firmware, Ge Multilin C70 Firmware, Ge Multilin C95 Firmware, Ge Multilin D30 Firmware, Ge Multilin D60 Firmware, Ge Multilin F35 Firmware, Ge Multilin F60 Firmware, Ge Multilin G30 Firmware, Ge Multilin G60 Firmware, Ge Multilin L30 Firmware, Ge Multilin L60 Firmware, Ge Multilin L90 Firmware, Ge Multilin M60 Firmware, Ge Multilin N60 Firmware, Ge Multilin T35 Firmware, Ge Multilin T60 Firmware.

## How do I fix CVE-2021-27420?

No fix has been published for CVE-2021-27420 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-27420 being exploited?

There is no known exploitation of CVE-2021-27420 in the wild and no public exploit code.

## Other vulnerabilities in GE UR family

- [CVE-2021-27426](https://insights.sbomify.com/CVE-2021-27426/): GE UR family insecure default variable initialization (critical 9.8)
- [CVE-2021-27428](https://insights.sbomify.com/CVE-2021-27428/): GE UR family Unrestricted Upload of File with Dangerous Type (critical 9.8)
- [CVE-2021-27422](https://insights.sbomify.com/CVE-2021-27422/): GE UR family exposure of sensitive information to an unauthorized actor (high 7.5)
- [CVE-2021-27418](https://insights.sbomify.com/CVE-2021-27418/): GE UR family input validation (medium 5.3)
- [CVE-2021-27424](https://insights.sbomify.com/CVE-2021-27424/): GE UR family exposure of sensitive information to an unauthorized actor (medium 5.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-27420 and fix it if it is affected.

What it is: CVE-2021-27420 is a medium-severity denial of service vulnerability in GE UR family, published on 23 Mar 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-27420 in the wild and no public exploit code.

Affected product: GE UR family. 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-2021-27420/ (Markdown: https://insights.sbomify.com/CVE-2021-27420/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-27420
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-27420
- OSV: https://osv.dev/vulnerability/CVE-2021-27420

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-27420/
Summaries are generated and may contain mistakes; the official description above is the record.