Signature checks not applied to some retrieved missing events
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Security bypass
- Confidentiality · integrity · availability
- Low · Low · Low
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-347.
Summary
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| matrix-org | dendrite | before 0.9.8 | 0.9.8 | Patch available | CNA |
| — | github.com/matrix-org/dendrite (Go) | before 0.9.8 | 0.9.8 | Patch available | GHSA-pfw4-xjgm-267c |
- dendrite Vendormatrix-org Affected before 0.9.8 Fixed in 0.9.8 Patch available CNA
- github.com/matrix-org/dendrite (Go) Vendor— Affected before 0.9.8 Fixed in 0.9.8 Patch available GHSA-pfw4-xjgm-267c
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:matrix:dendrite:*:*:*:*:*:*:*:* | before 0.9.8 | Vulnerable | matrix-org |
- cpe:2.3:a:matrix:dendrite:*:*:*:*:*:*:*:* Versions before 0.9.8 Vulnerable ·matrix-org
Remediation
- Fix · CNA dendrite (matrix-org) Fixed in 0.9.8
- Fix · GHSA-pfw4-xjgm-267c github.com/matrix-org/dendrite (Go) Fixed in 0.9.8 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2022-39200
- 2026-10-03 Alias added: GHSA-pfw4-xjgm-267c
References
More matrix-org Dendrite vulnerabilities
- TI-2022-16434 Incorrect parsing of access level in gomatrixserverlib and dendrite CVSS 3.1HIGH 8.8
Sources
- CVE-2022-39200 · CVE Program
- CVE-2022-39200 · NVD
- FIRST EPSS
- GHSA-pfw4-xjgm-267c · GitHub Advisory Database · CC BY 4.0
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