Loading
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.
Cite this page
CVE-2021-32659. CVEDatabase.com. Retrieved 1 May 2026. https://cvedatabase.com/cve/CVE-2021-32659
Use CWE-306, Matrix vendor hub and Matrix-Appservice-Bridge product page to widen CVE-2021-32659 into its surrounding weakness, vendor, and product context.
Compare it with CVE-2023-38691 for nearby disclosures in the same product family.