Wazuh: Heap Buffer Overflow in DecodeWinevt() join_data Accumulation via Crafted EventChannel XML

Wazuh is an open-source security platform providing unified XDR and SIEM protection for endpoints and cloud workloads. DecodeWinevt in src/analysisd/decoders/winevtchannel.c accumulates unnamed Windows EventChannel Data element contents into the fixed 65,535-byte join_data heap buffer but passes the growing content length, rather than the OS_MAXSTR buffer capacity, as the snprintf size. An enrolled agent can submit an EventChannel message containing four maximum-sized unnamed Data elements, causing the fourth accumulation to write beyond join_data and corrupt adjacent heap metadata. The subsequent free of join_data2 causes the wazuh-analysisd process to terminate, stopping log ingestion for all agents handled by that manager. This vulnerability is fixed in 4.14.7.