# CVE-2021-43667: NULL Pointer Dereference in HyperLedger Fabric

> Attackers can crash leader nodes in HyperLedger Fabric by sending messages with nil payloads, causing a denial of service.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/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:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 18 Nov 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-vjj6-5m9f-wqjw

## What is CVE-2021-43667?

CVE-2021-43667 is a high-severity vulnerability in n/a, published on 18 Nov 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability has been detected in HyperLedger Fabric v1.4.0, v2.0.0, v2.1.0. This bug can be leveraged by constructing a message whose payload is nil and sending this message with the method 'forwardToLeader'. This bug has been admitted and fixed by the developers of Fabric. If leveraged, any leader node will crash.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2021-43667?

4 open source packages ship an affected version, including github.com/hyperledger/fabric. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/hyperledger/fabric` | Go | All versions | 2.2.4 |
| `github.com/hyperledger/fabric` | Go | All versions | 2.2.4 |
| `github.com/hyperledger/fabric` | Go | From 2.3.0 | 2.3.3 |
| `github.com/hyperledger/fabric` | Go | From 2.3.0 | 2.3.3 |

Products: Linuxfoundation Fabric.

## How do I fix CVE-2021-43667?

Upgrade github.com/hyperledger/fabric to a fixed version for your release line: 2.2.4 or 2.3.3.

## Is CVE-2021-43667 being exploited?

There is no known exploitation of CVE-2021-43667 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2021-43669](https://insights.sbomify.com/CVE-2021-43669/): HTTP Request Smuggling in github.com/hyperledger/fabric (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-43667 and fix it if it is affected.

What it is: CVE-2021-43667 is a high-severity vulnerability in n/a, published on 18 Nov 2021. 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-2021-43667 in the wild and no public exploit code.

Affected packages and fixed versions:
- github.com/hyperledger/fabric (Go): affected all versions; fixed in 2.2.4
- github.com/hyperledger/fabric (Go): affected all versions; fixed in 2.2.4
- github.com/hyperledger/fabric (Go): affected from 2.3.0; fixed in 2.3.3
- github.com/hyperledger/fabric (Go): affected from 2.3.0; fixed in 2.3.3

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-2021-43667/ (Markdown: https://insights.sbomify.com/CVE-2021-43667/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-43667
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-43667
- OSV: https://osv.dev/vulnerability/CVE-2021-43667

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-43667/
Summaries are generated and may contain mistakes; the official description above is the record.