What is CVE-2022-36009?

CVE-2022-36009 is a medium-severity vulnerability in Matrix Dendrite, classified under Incorrect Authorization. CVSS score: 5.0/10. Published 2022-08-19.

How severe is CVE-2022-36009?

Medium severity. CVSS v3 base score is 5.0 out of 10.

Auth bypass in Matrix Dendrite

CVE-2022-36009

gomatrixserverlib is a Go library for matrix protocol federation. Dendrite is a Matrix homeserver written in Go, an alternative to Synapse. The power level parsing within gomatrixserverlib was failing to parse the `"events_default"` key of the `m.room.power_levels` event, defaulting the event default power level to zero in all cases. Power levels are the matrix terminology for user access level. In rooms where the `"events_default"` power level had been changed, this could result in events either being incorrectly authorised or rejected by Dendrite servers. gomatrixserverlib contains a fix as of commit `723fd49` and Dendrite 0.9.3 has been updated accordingly. Matrix rooms where the `"events_default"` power level has not been changed from the default of zero are not vulnerable. Users are advised to upgrade. There are no known workarounds for this issue.

Vulnerability class: Broken Access Control

Published 2022-08-19 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.0 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L.

EPSS exploit prediction

EPSS: 0.008 (55.4th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 55th percentile — 55.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.008 · newest: 0.008 · change: +0.000

Affected products

Matrix Dendrite
Matrix Gomatrixserverlib
Matrix-Org Gomatrixserverlib — versions < 0.9.3 for dendrite, < 723fd49 for gomatrixserverlib

Weakness classification (CWE)

CWE-863 — Incorrect Authorization

References

github.com/matrix-org/gomatrixserverlib/security/advisories/GHSA-grvv-h2f9-7v9c (Third Party Advisory)
github.com/matrix-org/gomatrixserverlib/commit/723fd495dde835d078b9f2074b6b62c0… (Patch, Third Party Advisory)
matrix.org/docs/guides/moderation/ (Vendor Advisory)

Frequently asked questions

What is CVE-2022-36009?: CVE-2022-36009 is a medium-severity vulnerability in Matrix Dendrite, classified under Incorrect Authorization. CVSS score: 5.0/10. Published 2022-08-19.
How severe is CVE-2022-36009?: Medium severity. CVSS v3 base score is 5.0 out of 10.