# CVE-2022-39200: Signature checks not applied to some retrieved missing events

> A remote homeserver can inject invalid or modified events into Dendrite via the get_missing_events endpoint due to missing signature verification.

- **Severity:** High 7.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 12 Sep 2022
- **Updated:** 23 Apr 2025
- **Also known as:** GHSA-pfw4-xjgm-267c, GO-2022-0989

## What is CVE-2022-39200?

CVE-2022-39200 is a high-severity vulnerability in matrix-org dendrite, published on 12 Sep 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Dendrite is a Matrix homeserver written in Go. In affected versions events retrieved from a remote homeserver using the `/get_missing_events` path did not have their signatures verified correctly. This could potentially allow a remote homeserver to provide invalid/modified events to Dendrite via this endpoint. Note that this does not apply to events retrieved through other endpoints (e.g. `/event`, `/state`) as they have been correctly verified. Homeservers that have federation disabled are not vulnerable. The problem has been fixed in Dendrite 0.9.8. Users are advised to upgrade. There are no known workarounds for this issue.

Weakness: CWE-347 (Improper Verification of Cryptographic Signature)

## Which versions are affected by CVE-2022-39200?

3 open source packages ship an affected version, including github.com/matrix-org/dendrite. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/matrix-org/dendrite` | Go | All versions | 0.9.8 |
| `github.com/matrix-org/dendrite` | Go | All versions | 0.9.8 |
| `github.com/matrix-org/dendrite` | Go | All versions | 0.9.8 |

Products: Matrix Dendrite.

## How do I fix CVE-2022-39200?

Upgrade github.com/matrix-org/dendrite to 0.9.8 or later.

## Is CVE-2022-39200 being exploited?

There is no known exploitation of CVE-2022-39200 in the wild and no public exploit code.

## Other vulnerabilities in matrix-org dendrite

- [CVE-2022-36009](https://insights.sbomify.com/CVE-2022-36009/): Incorrect parsing of access level in gomatrixserverlib and dendrite (medium 5.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2022-39200 and fix it if it is affected.

What it is: CVE-2022-39200 is a high-severity vulnerability in matrix-org dendrite, published on 12 Sep 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-2022-39200 in the wild and no public exploit code.

Affected packages and fixed versions:
- github.com/matrix-org/dendrite (Go): affected all versions; fixed in 0.9.8
- github.com/matrix-org/dendrite (Go): affected all versions; fixed in 0.9.8
- github.com/matrix-org/dendrite (Go): affected all versions; fixed in 0.9.8

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-2022-39200/ (Markdown: https://insights.sbomify.com/CVE-2022-39200/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2022-39200
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2022-39200
- OSV: https://osv.dev/vulnerability/CVE-2022-39200

---
From sbomify Insights: https://insights.sbomify.com/CVE-2022-39200/
Summaries are generated and may contain mistakes; the official description above is the record.