Corosync Totem Heap Buffer Overflow in Message Reassembly

CVE-2026-81665 represents a critical vulnerability in Corosync's Totem Process Group (totempg) message reassembly logic, where fragmented multicast messages are processed without proper runtime bounds checking in release builds. This heap-based buffer overflow allows network-adjacent attackers to inject crafted multicast protocol messages that corrupt heap memory with attacker-controlled data. Organizations running Corosync for high-availability clustering—including Red Hat Enterprise Linux clusters, Kubernetes infrastructure, and distributed database systems—face immediate risk of denial of service when this vulnerability is exploited, potentially taking entire cluster infrastructures offline.

While MITRE ATT&CK mapping is not yet available for this CVE, Casky's 754 security skills and Claude AI's extended reasoning enable detection of the attack patterns underlying this vulnerability. Practitioners using Casky would identify suspicious indicators including abnormal multicast traffic patterns with fragmented messages, unexpected heap memory corruption signatures in Corosync daemon logs, and process crashes tied to specific message sequence patterns. The platform's skill set would correlate these technical indicators with resource exhaustion and process termination behaviors, allowing security teams to detect exploitation attempts before cluster-wide denial of service occurs. Casky's analysis would help practitioners distinguish between legitimate fragmented multicast reassembly and malicious packet crafting attempts targeting the bounds-checking gap.