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 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.
Disable the provisioning API. If the bridge does not use the provisioning API, you are not vulnerable.
{ "nvd_published_at": "2023-08-04T17:15:11Z", "cwe_ids": [ "CWE-287" ], "severity": "MODERATE", "github_reviewed": true, "github_reviewed_at": "2023-08-04T17:26:32Z" }