Headline
GHSA-grvv-h2f9-7v9c: gomatrixserverlib and Dendrite vulnerable to incorrect parsing of the event default power level in event auth
Impact
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.
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.
Patches
gomatrixserverlib contains a fix as of commit 723fd49 and Dendrite 0.9.3 has been updated accordingly.
Workarounds
Matrix rooms where the "events_default" power level has not been changed from the default of zero are not vulnerable.
For more information
If you have any questions or comments about this advisory, e-mail us at [email protected].
Impact
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.
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.
Patches
gomatrixserverlib contains a fix as of commit 723fd49 and Dendrite 0.9.3 has been updated accordingly.
Workarounds
Matrix rooms where the “events_default” power level has not been changed from the default of zero are not vulnerable.
For more information
If you have any questions or comments about this advisory, e-mail us at [email protected].
References
- GHSA-grvv-h2f9-7v9c
- https://nvd.nist.gov/vuln/detail/CVE-2022-36009
- matrix-org/gomatrixserverlib@723fd49
- https://matrix.org/docs/guides/moderation/#power-levels
Related news
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.