CVE-2023-38686
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.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
Package impact
| Ecosystem | Package | Vulnerable | Fixed |
|---|---|---|---|
| PyPI | matrix-sydent | <2.5.6 | 2.5.6 |
| PyPI | matrix-sydent | <1cd748307c6b168b66154e6c4db715d4b9551261||<2.5.6 | 1cd748307c6b168b66154e6c4db715d4b9551261 |
References
- https://github.com/matrix-org/sydent/security/advisories/GHSA-p6hw-wm59-3g5g
- https://nvd.nist.gov/vuln/detail/CVE-2023-38686
- https://github.com/python/cpython/issues/91826
- https://github.com/matrix-org/sydent/pull/574
- https://github.com/matrix-org/sydent/commit/1cd748307c6b168b66154e6c4db715d4b9551261
- https://docs.python.org/3/library/ssl.html?highlight=ssl#security-considerations
- https://github.com/matrix-org/sydent
- https://github.com/matrix-org/sydent/releases/tag/v2.5.6
- https://github.com/pypa/advisory-database/tree/main/vulns/matrix-sydent/PYSEC-2023-139.yaml
- https://peps.python.org/pep-0476
- https://peps.python.org/pep-0476/
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.