A flaw has been found in Hazelcast Enterprise Edition and Community Edition, which would allow a low-privileged malicious client to read arbitrary data in memory from any cluster member (including Java heap memory, off-heap data, and JVM process address space). Additionally, such a client may be able to cause one or more cluster members to crash, or in some Enterprise Edition configurations also corrupt memory contents, potentially leading to remote code execution. Both slim and full distributions are affected.

Enterprise customers should upgrade to a fixed version of Hazelcast Enterprise Edition:

Customers with extended support contracts should contact Hazelcast Support for information on patches for older versions.

Community Edition users should upgrade to version 5.7.0.

Hazelcast also recommends all customers follow the advice in our Security Hardening guide, including:

If you cannot update to a fixed version immediately, restrict cluster access to trusted clients only and ensure clients are hardened against compromise.