cvedb.io
CVE-2021-32659
MEDIUM · CVSS 6.5
EPSS exploitation probability: 0%
Published 2021-06-16T19:15:38.830 · Last modified 2026-06-17T03:53:22.010

Summary

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 `roomUpgr

Affected products

matrix — matrix-appservice-bridge

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References

This product uses data from the NVD API but is not endorsed or certified by the NVD. Informational only; not professional security advice.