Vulnerability Description
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.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Matrix | Matrix-Appservice-Bridge | >= 4.0.0, < 8.1.2 |
Related Weaknesses (CWE)
References
- https://github.com/matrix-org/matrix-appservice-bridge/commit/4c6723a5e7beda65cdPatch
- https://github.com/matrix-org/matrix-appservice-bridge/security/advisories/GHSA-Third Party Advisory
- https://github.com/matrix-org/matrix-appservice-bridge/commit/4c6723a5e7beda65cdPatch
- https://github.com/matrix-org/matrix-appservice-bridge/security/advisories/GHSA-Third Party Advisory
FAQ
What is CVE-2023-38691?
CVE-2023-38691 is a vulnerability with a CVSS score of 5.0 (MEDIUM). 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 e...
How severe is CVE-2023-38691?
CVE-2023-38691 has been rated MEDIUM with a CVSS base score of 5.0/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2023-38691?
Check the references section above for vendor advisories and patch information. Affected products include: Matrix Matrix-Appservice-Bridge.