CVE-2021-32659

Severity CVSS v4.0:

Pending analysis

Type:

CWE-306 Missing Authentication for Critical Function

Publication date:

16/06/2021

Last modified:

09/07/2021

Description

Matrix-appservice-bridge is the bridging service for the Matrix communication program&#39;s application services. In versions 2.6.0 and earlier, if a bridge has room upgrade handling turned on in the configuration (the `roomUpgradeOpts` key when instantiating a new `Bridge` instance.), any `m.room.tombstone` event it encounters will be used to unbridge the current room and bridge into the target room. However, the target room `m.room.create` event is not checked to verify if the `predecessor` field contains the previous room. This means that any malicious admin of a bridged room can repoint the traffic to a different room without the new room being aware. Versions 2.6.1 and greater are patched. As a workaround, disabling the automatic room upgrade handling can be done by removing the `roomUpgradeOpts` key from the `Bridge` class options.

Impact

Vector 3.x

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N CVSS v3.1 Severity and Metrics:

Base Score: 4.90 MEDIUM
Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N

Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): High
User Interaction (UI): None
Scope (S): Unchanged
Confidentiality (C): None
Integrity (I): High
Availability (A): None

Base Score 3.x

4.90

Severity 3.x

MEDIUM

Vector 2.0

AV:N/AC:M/Au:S/C:N/I:P/A:N CVSS v2.0 Severity and Metrics:

Base Score: 3.50 LOW
Vector: AV:N/AC:M/Au:S/C:N/I:P/A:N

Attack Vector (AV): Network
Attack Complexity (AC): Medium
Authentication (Au): Single
Confidentiality (C): None
Integrity (I): Physical
Availability (A): None