CVE-2020-15134
Description
Faye before version 1.4.0, there is a lack of certification validation in TLS handshakes. Faye uses em-http-request and faye-websocket in the Ruby version of its client. Those libraries both use the `EM::Connection#start_tls` method in EventMachine to implement the TLS handshake whenever a `wss:` URL is used for the connection. This method does not implement certificate verification by default, meaning that it does not check that the server presents a valid and trusted TLS certificate for the expected hostname. That means that any `https:` or `wss:` connection made using these libraries is vulnerable to a man-in-the-middle attack, since it does not confirm the identity of the server it is connected to. The first request a Faye client makes is always sent via normal HTTP, but later messages may be sent via WebSocket. Therefore it is vulnerable to the same problem that these underlying libraries are, and we needed both libraries to support TLS verification before Faye could claim to do the same. Your client would still be insecure if its initial HTTPS request was verified, but later WebSocket connections were not. This is fixed in Faye v1.4.0, which enables verification by default. For further background information on this issue, please see the referenced GitHub Advisory.
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.
OS impact
Debian Fixed 2 releases
| Version | Status | Fixed in |
|---|---|---|
| bullseye | Fixed | 1.4.0-1 |
| bookworm | Fixed | 1.4.0-1 |
References
- https://github.com/faye/faye/security/advisories/GHSA-3q49-h8f9-9fr9
- https://nvd.nist.gov/vuln/detail/CVE-2020-15134
- https://github.com/eventmachine/eventmachine/issues/275
- https://github.com/eventmachine/eventmachine/issues/814
- https://github.com/faye/faye/issues/524
- https://github.com/eventmachine/eventmachine/pull/378
- https://github.com/faye/faye-websocket-ruby/pull/129
- https://github.com/igrigorik/em-http-request/pull/340
- https://blog.jcoglan.com/2020/07/31/missing-tls-verification-in-faye
- https://github.com/faye/faye
- https://github.com/rubysec/ruby-advisory-db/blob/master/gems/faye/CVE-2020-15134.yml
- https://securitylab.github.com/advisories/GHSL-2020-094-igrigorik-em-http-request
- https://www.rubydoc.info/github/eventmachine/eventmachine/EventMachine/Connection:ssl_verify_peer
- https://www.rubydoc.info/github/eventmachine/eventmachine/EventMachine/Connection:start_tls
- https://security-tracker.debian.org/tracker/CVE-2020-15134
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.