ctcphandler.cpp in Quassel before 0.6.3 and 0.7.x before 0.7.1 allows remote attackers to cause a denial of service (unresponsive IRC) via multiple Client-To-Client Protocol (CTCP) requests in a PRIVMSG message.

The CtcpParser::packedReply method in core/ctcpparser.cpp in Quassel before 0.7.3 allows remote attackers to cause a denial of service (crash) via a crafted Client-To-Client Protocol (CTCP) request, as demonstrated in the wild in September 2011.

SQL injection vulnerability in Quassel IRC before 0.9.1, when Qt 4.8.5 or later and PostgreSQL 8.2 or later are used, allows remote attackers to execute arbitrary SQL commands via a \ (backslash) in a message.

Quassel core (server daemon) in Quassel IRC before 0.9.2 does not properly verify the user ID when accessing user backlogs, which allows remote authenticated users to read other users' backlogs via the bufferid in (1) 16/select_buffer_by_id.sql, (2) 16/select_buffer_by_id.sql, and (3) 16/select_buffer_by_id.sql in core/SQL/PostgreSQL/.

The blowfishECB function in core/cipher.cpp in Quassel IRC 0.10.0 allows remote attackers to cause a denial of service (out-of-bounds read) via a malformed string.

Quassel before 0.12-rc1 uses an incorrect data-type size when splitting a message, which allows remote attackers to cause a denial of service (crash) via a long CTCP query containing only multibyte characters.

Stack consumption vulnerability in the message splitting functionality in Quassel before 0.12-rc1 allows remote attackers to cause a denial of service (uncontrolled recursion) via a crafted massage.

Quassel before 0.12.2 does not properly re-initialize the database session when the PostgreSQL database is restarted, which allows remote attackers to conduct SQL injection attacks via a \ (backslash) in a message. NOTE: this vulnerability exists because of an incomplete fix for CVE-2013-4422.

The CoreUserInputHandler::doMode function in core/coreuserinputhandler.cpp in Quassel 0.10.0 allows remote attackers to cause a denial of service (application crash) via the "/op *" command in a query.

The onReadyRead function in core/coreauthhandler.cpp in Quassel before 0.12.4 allows remote attackers to cause a denial of service (NULL pointer dereference and crash) via invalid handshake data.

A heap corruption of type CWE-120 exists in quassel version 0.12.4 in quasselcore in void DataStreamPeer::processMessage(const QByteArray &msg) datastreampeer.cpp line 62 that allows an attacker to execute code remotely.

A NULL Pointer Dereference of CWE-476 exists in quassel version 0.12.4 in the quasselcore void CoreAuthHandler::handle(const Login &msg) coreauthhandler.cpp line 235 that allows an attacker to cause a denial of service.

Quassel through 0.13.1, when --require-ssl is enabled, launches without SSL or TLS support if a usable X.509 certificate is not found on the local system.