In ZeroMQ libzmq before 4.0.9, 4.1.x before 4.1.7, and 4.2.x before 4.3.2, a remote, unauthenticated client connecting to a libzmq application, running with a socket listening with CURVE encryption/authentication enabled, may cause a stack overflow and overwrite the stack with arbitrary data, due to a buffer overflow in the library. Users running public servers with the above configuration are highly encouraged to upgrade as soon as possible, as there are no known mitigations.

A pointer overflow, with code execution, was discovered in ZeroMQ libzmq (aka 0MQ) 4.2.x and 4.3.x before 4.3.1. A v2decoder.cpp zmq::v2decodert::sizeready integer overflow allows an authenticated attacker to overwrite an arbitrary amount of bytes beyond the bounds of a buffer, which can be leveraged to run arbitrary code on the target system. The memory layout allows the attacker to inject OS commands into a data structure located immediately after the problematic buffer (i.e., it is not necessary to use a typical buffer-overflow exploitation technique that changes the flow of control).

A flaw was found in zeromq before 4.3.3. The use of a static allocator with ZMTP v1 packets may lead to a heap based overflow.

References:

https://github.com/zeromq/libzmq/pull/3902 https://github.com/zeromq/libzmq/security/advisories/GHSA-fc3w-qxf5-7hp6 https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=21984

A flaw was found in zeromq before 4.3.3. Messages with metadata are never processed by PUB sockets, but the metadata is kept referenced in the PUB object and never freed leading to memory leaks.

References:

https://github.com/zeromq/libzmq/pull/3935 https://github.com/zeromq/libzmq/security/advisories/GHSA-4p5v-h92w-6wxw https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=22344