Automatic room upgrade handling can be used maliciously to bridge a room non-consentually

中 4.9CVE-2021-32659 · GHSA-35g4-qx3c-vjhx · 16/06/2021 公開 · 17/06/2026 更新

要点

CVE-2021-32659 は matrix-appservice-bridge (matrix), matrix-appservice-bridge に影響する深刻度「中」 (CVSS 4.9) の脆弱性です。
今後30日間に悪用される確率（EPSS）：0.94%（全脆弱性の 60.8% より高い）。
対処：2.6.1 以降に更新してください。

パッケージ	影響を受けるバージョン	修正済みバージョン
matrix-appservice-bridge matrix	`< 2.6.1`	`2.6.1`
matrix-appservice-bridge npm	`< 2.6.1`	`2.6.1`

概要

Impact

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 mailcious admin of a bridged room can repoint the traffic to a different room without the new room being aware.

Patches

Versions 2.6.1 and greater are patched.

Workarounds

Disabling the automatic room upgrade handling can be done by removing the roomUpgradeOpts key from the Bridge class options.

References

The issue is patched by https://github.com/matrix-org/matrix-appservice-bridge/pull/330

For more information]

If you have any questions or comments about this advisory, email us at [email protected].

NVD の説明

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.