CVE-2022-36009 Information

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 vents_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 vents_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 vents_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.

Reference

https://github.com/matrix-org/gomatrixserverlib/commit/723fd495dde835d078b9f2074b6b62c06dea4575 https://matrix.org/docs/guides/moderation/#power-levels https://github.com/matrix-org/gomatrixserverlib/security/advisories/GHSA-grvv-h2f9-7v9c