CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS
Percentile
42.8%
Attackers can specify a specific string of characters, which would confuse the bridge into combining an attacker-owned channel and an existing channel, allowing them to grant themselves permissions in the channel.
The vulnerability has been patched in matrix-appservice-irc 0.35.0.
Disable dynamic channel joining via dynamicChannels.enabled
to prevent users from joining new channels, which prevents any new channels being bridged outside of what is already bridged, and what is specified in the config.
Discovered and reported by Val Lorentz.
If you have any questions or comments about this advisory email us at [email protected].