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
EPSS: 0.007 (48.0th percentile) — read the EPSS interpretation.
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.
Affected products
- Matrix Dendrite
- Matrix Gomatrixserverlib
- Matrix-org Gomatrixserverlib — versions < 0.9.3 for dendrite, < 723fd49 for gomatrixserverlib
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM, Third Party Advisory)
- security-advisories@github.com (Patch, Third Party Advisory, x_refsource_MISC)
- security-advisories@github.com (x_refsource_MISC, 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.