Vulnerability Description
Sydent is an identity server for the Matrix communications protocol. Prior to version 2.5.6, if configured to send emails using TLS, Sydent does not verify SMTP servers' certificates. This makes Sydent's emails vulnerable to interception via a man-in-the-middle (MITM) attack. Attackers with privileged access to the network can intercept room invitations and address confirmation emails. This is patched in Sydent 2.5.6. When patching, make sure that Sydent trusts the certificate of the server it is connecting to. This should happen automatically when using properly issued certificates. Those who use self-signed certificates should make sure to copy their Certification Authority certificate, or their self signed certificate if using only one, to the trust store of your operating system. As a workaround, one can ensure Sydent's emails fail to send by setting the configured SMTP server to a loopback or non-routable address under one's control which does not have a listening SMTP server.
CVSS Score
CRITICAL
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Matrix | Sydent | < 2.5.6 |
Related Weaknesses (CWE)
References
- https://docs.python.org/3/library/ssl.html?highlight=ssl#security-considerationsTechnical Description
- https://github.com/matrix-org/sydent/commit/1cd748307c6b168b66154e6c4db715d4b955Patch
- https://github.com/matrix-org/sydent/pull/574Issue TrackingPatch
- https://github.com/matrix-org/sydent/releases/tag/v2.5.6Release Notes
- https://github.com/matrix-org/sydent/security/advisories/GHSA-p6hw-wm59-3g5gVendor Advisory
- https://github.com/python/cpython/issues/91826Issue Tracking
- https://peps.python.org/pep-0476/Third Party Advisory
- https://docs.python.org/3/library/ssl.html?highlight=ssl#security-considerationsTechnical Description
- https://github.com/matrix-org/sydent/commit/1cd748307c6b168b66154e6c4db715d4b955Patch
- https://github.com/matrix-org/sydent/pull/574Issue TrackingPatch
- https://github.com/matrix-org/sydent/releases/tag/v2.5.6Release Notes
- https://github.com/matrix-org/sydent/security/advisories/GHSA-p6hw-wm59-3g5gVendor Advisory
- https://github.com/python/cpython/issues/91826Issue Tracking
- https://peps.python.org/pep-0476/Third Party Advisory
FAQ
What is CVE-2023-38686?
CVE-2023-38686 is a vulnerability with a CVSS score of 9.3 (CRITICAL). Sydent is an identity server for the Matrix communications protocol. Prior to version 2.5.6, if configured to send emails using TLS, Sydent does not verify SMTP servers' certificates. This makes Syde...
How severe is CVE-2023-38686?
CVE-2023-38686 has been rated CRITICAL with a CVSS base score of 9.3/10. This is considered a critical vulnerability requiring immediate attention.
Is there a patch for CVE-2023-38686?
Check the references section above for vendor advisories and patch information. Affected products include: Matrix Sydent.