Description
Matrix-appservice-bridge is the bridging service for the Matrix communication program'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.
Analysis and contextual insights are available on OpenCVE Cloud.
Remediation
No vendor fix or workaround currently provided.
Additional remediation guidance may be available on OpenCVE Cloud.
Tracking
Sign in to view the affected projects.
Advisories
| Source | ID | Title |
|---|---|---|
EUVD |
EUVD-2021-1248 | Matrix-appservice-bridge is the bridging service for the Matrix communication program'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. |
Github GHSA |
GHSA-35g4-qx3c-vjhx | Automatic room upgrade handling can be used maliciously to bridge a room non-consentually |
References
History
Tue, 24 Feb 2026 17:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Title | Automatic room upgrade handling can be used maliciously to bridge a room non-consentually | Automatic room upgrade handling can be used maliciously to bridge a room non-consentually |
Status: PUBLISHED
Assigner: GitHub_M
Published:
Updated: 2024-08-03T23:25:31.074Z
Reserved: 2021-05-12T00:00:00.000Z
Link: CVE-2021-32659
No data.
Status : Modified
Published: 2021-06-16T19:15:38.830
Modified: 2024-11-21T06:07:28.667
Link: CVE-2021-32659
No data.
OpenCVE Enrichment
No data.
Weaknesses
EUVD
Github GHSA