GHSA-vc7j-h8xg-fv5x
matrix-appservice-bridge doesn't verify the sub parameter of an openId token exhange, allowing unauthorized access to provisioning APIs
Quick fix
GHSA-vc7j-h8xg-fv5x — matrix-appservice-bridge: upgrade to the fixed version with the command below.
npm install matrix-appservice-bridge@8.1.2Details
### Impact
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.
### Details
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.
### Workarounds
Disable the provisioning API. If the bridge does not use the provisioning API, you are not vulnerable.
Are you affected?
Enter the version of the package you're using.
Affected packages
4.0.0Fixed in: 8.1.2npm install matrix-appservice-bridge@8.1.29.0.0Fixed in: 9.0.1npm install matrix-appservice-bridge@9.0.1References
- https://github.com/matrix-org/matrix-appservice-bridge/security/advisories/GHSA-vc7j-h8xg-fv5x[WEB]
- https://nvd.nist.gov/vuln/detail/CVE-2023-38691[ADVISORY]
- https://github.com/matrix-org/matrix-appservice-bridge/commit/4c6723a5e7beda65cdf1ae5dbb882e8beaac8552[WEB]
- https://github.com/matrix-org/matrix-appservice-bridge[PACKAGE]