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CVE-2021-32659— Automatic room upgrade handling can be used maliciously to bridge a room non-consentually

Quick assessment

Affected
matrix-org matrix-appservice-bridge
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Matrix-appservice-bridge是开源的一个服务。用于Matrix通信程序的应用服务的桥接。 Matrix-appservice-bridge 存在安全漏洞，该漏洞源于在版本2.6.0及更早的版本中，如果网桥在配置中打开了房间升级处理（实例化新的“Bridge”实例时的“roomUpgradeOpts”键。），它遇到的任何“m.room.tombstone”事件都将是用于解除当前房间的桥接并连接到目标房间。 但是，不会检查目标房间 事件以验证 `predec

CVSS 6.5 · Medium EPSS 0.94% · P59

Possible ATT&CK Techniques 1 AI

T1530 · Data from Cloud Storage
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I. Basic Information for CVE-2021-32659

Vulnerability Information
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Vulnerability Title
Automatic room upgrade handling can be used maliciously to bridge a room non-consentually
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
关键功能的认证机制缺失
Source: CVE Program / CVE List V5
Vulnerability Title
Matrix-appservice-bridge 访问控制错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Matrix-appservice-bridge是开源的一个服务。用于Matrix通信程序的应用服务的桥接。 Matrix-appservice-bridge 存在安全漏洞，该漏洞源于在版本2.6.0及更早的版本中，如果网桥在配置中打开了房间升级处理（实例化新的“Bridge”实例时的“roomUpgradeOpts”键。），它遇到的任何“m.room.tombstone”事件都将是用于解除当前房间的桥接并连接到目标房间。 但是，不会检查目标房间 `m.room.create` 事件以验证 `predec
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
matrix-org matrix-appservice-bridge < 2.6.1 -

II. Public POCs for CVE-2021-32659

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III. Intelligence Information for CVE-2021-32659

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Patches & Fixes for CVE-2021-32659 (1)

Vendor Advisories for CVE-2021-32659 (1)

Other References for CVE-2021-32659 (1)

IV. Related Vulnerabilities

Same product: matrix-appservice-bridge
Same vendor: matrix-org
Same weakness: CWE-306

V. Comments for CVE-2021-32659

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