matrix-appservice-bridge provides an API for setting up bridges. Starting in version 4.0.0 and prior to versions 8.1.2 and 9.0.1, a malicious Matrix server can use a foreign user's MXID in an OpenID exchange, allowing a bad actor to impersonate users when using the provisioning API. The library does not check that the servername part of the `sub` parameter (containing the user's *claimed* MXID) is the the same as the servername we are talking to. A malicious actor could spin up a server on any given domain, respond with a `sub` parameter according to the user they want to act as and use the resulting token to perform provisioning requests. Versions 8.1.2 and 9.0.1 contain a patch. As a workaround, disable the provisioning API.
History

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published: 2023-08-04T16:34:54.312Z

Updated: 2024-08-02T17:46:56.516Z

Reserved: 2023-07-24T16:19:28.364Z

Link: CVE-2023-38691

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Analyzed

Published: 2023-08-04T17:15:11.063

Modified: 2023-08-11T19:34:52.207

Link: CVE-2023-38691

cve-icon Redhat

No data.