CVE-2022-36009 is a medium-severity (CVSS 5) CWE-863 vulnerability in github.com/matrix-org/dendrite. A fix is available for github.com/matrix-org/dendrite — see the affected versions and patch details below.
Incorrect parsing of access level in gomatrixserverlib and dendrite
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2022-36009.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
github.com/matrix-org/dendrite🐹github.com/matrix-org/gomatrixserverlibReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/matrix-org/dendrite | all versions | 0.9.3go get github.com/matrix-org/dendrite@v0.9.3 |
| 🐹Go | github.com/matrix-org/gomatrixserverlib | all versions | 0.0.0-20220815091947-723fd495dde8go get github.com/matrix-org/gomatrixserverlib@v0.0.0-20220815091947-723fd495dde8 |
Affected Products
dendritematrixgomatrixserverlibmatrixDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/matrix-org/dendrite, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/matrix-org/dendrite to 0.9.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2022-36009 is resolved across your whole dependency graph.
Workarounds
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.
Frequently Asked Questions
Is CVE-2022-36009 in your dependencies?
Find it across Go, including transitive dependencies.