CVEvulnerability

CVE-2023-38691

6.5 MEDIUM Published 2023-08-04 Modified 2026-06-17 Official page ↗
Status
Modified
Published
2023-08-04
Last modified
2026-06-17
Assigner
[email protected]
CVSS 3.1 ([email protected])
5.0 MEDIUM — CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:N
CVSS 3.1 ([email protected])
6.5 MEDIUM — CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Weaknesses
CWE-287

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.

Affected configurations

• matrix matrix-appservice-bridge (>= 4.0.0 < 8.1.2) • matrix matrix-appservice-bridge 9.0.0

Related

Weakness · CWE (1)

  • CWE-287 Improper Authentication weakness

References