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 provision
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)…
| Vendor | Product | Versions |
|---|---|---|
| matrix-org | matrix | appservice-bridge — >= 4.0.0, < 8.1.2, = 9.0.0 |
Not currently listed on the CISA Known Exploited Vulnerabilities (KEV) catalog. EPSS is the best forward-looking signal — see the EPSS row above.
For the full vendor write-up, exploit chains, and reference implementations, see the references list in section 09.
Open the Sigma generator with a pre-filled prompt for this CVE to draft a starting detection in your stack of choice:
No directly-cited follow-up CVEs in the KB record for this advisory. The references list in section 09 carries the vendor cross-references.