Concurrent Acknowledgment Issue in Linux Kernel Affecting Group Broadcast Functionality

CVE-2026-31662

What is CVE-2026-31662?

A notable vulnerability in the Linux kernel pertains to the handling of group acknowledgment messages (GRP_ACK_MSG) within the TIPC (Transparent Inter-Process Communication) framework. When duplicate acknowledgments are received, the handler erroneously decrements the bc_ackers value, which can lead to an underflow condition. This underflow occurs due to the limited range of a u16 data type, resulting in erroneous congestion reporting and blocking of subsequent group broadcasts until the affected group is recreated. The issue has been rectified by ensuring that duplicate or stale acknowledgments are ignored, thus maintaining the integrity of the acknowledgment process and preventing underflow issues.

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