GHSA-grvv-h2f9-7v9c

### 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]](mailto:[email protected]).