It doesn't seem to be possible to disable SSLv3.
SSLv3 is considered harmful (see CVE-2014-3566 aka POODLE) but it seems to be used by default for QuasselCore / Client.
As far as I understand the default ssl protocol for QSslSocket is SSLv3 and TLSv1.0 (that is covered by QSsl::SecureProtocol enum value which is the default). There is a fix in Qt to not include SSLv3 in QSsl::SecureProtocols however it hasn't been released yet (and seems to be in upcoming 5.4 only - https://qt.gitorious.org/qt/qtbase/commit/3fd2d9eff8c1f948306ee5fbfe364ccded1c4b84).
It would be great if it is possible to enforce TLS-only connections with Quassel.
Hi there. I'm going through the backlog of bugs in the queue and handling ones I think I can help out with.
I've just done a test with openssl s_client, on quasselcore built from source, and my build is only supporting TLS 1.0, 1.1 and 1.2. No SSLv3 is supported. I also tested the Fedora-packaged Quasselcore (0.13.1) and it also does not support SSLv3. I do not believe that any modern builds of Quassel support SSLv3 anymore.
In testing this bug, I also discovered #1728, which currently has a PR submitted to fix. Once that is merged, this bug should be good to close.