CVE-2026-31662High· 7.5▾ TwilightIn the Linux kernel, the following vulnerability has been resolved: tipc: fix bc_ackers underflow on duplicate GRP_ACK_MSG The GRP_ACK_MSG handler in tipc_group_proto_rcv() currently decrements bc_ackers on every inbound group ACK, eve…
▾ Twilight zone — High severity, or a signal on a lesser flaw
impact 41.3 · likelihood 0.1 · exploitation 0
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Stakeholder-Specific Vulnerability Categorization from CISA's ADP record at CVE.org: whether exploitation is observed, whether an attack can be automated, and how much of the system is at stake. The CVSS score shown above comes from the assigning CNA record, not NVD.
Exploit-prediction probability, daily snapshots since Oct 16.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via CVEORG
0.4%
Last analysed / modified upstream
In the Linux kernel, the following vulnerability has been resolved:
tipc: fix bc_ackers underflow on duplicate GRP_ACK_MSG
The GRP_ACK_MSG handler in tipc_group_proto_rcv() currently decrements bc_ackers on every inbound group ACK, even when the same member has already acknowledged the current broadcast round.
Because bc_ackers is a u16, a duplicate ACK received after the last legitimate ACK wraps the counter to 65535. Once wrapped, tipc_group_bc_cong() keeps reporting congestion and later group broadcasts on the affected socket stay blocked until the group is recreated.
Fix this by ignoring duplicate or stale ACKs before touching bc_acked or bc_ackers. This makes repeated GRP_ACK_MSG handling idempotent and prevents the underflow path.
Linux >= 2f487712b89376fce267223bbb0db93d393d4b09 < a7db57ccca21f5801609065473c89a38229ecb92Linux >= 2f487712b89376fce267223bbb0db93d393d4b09 < 36ec4fdd6250dcd5e73eb09ea92ed92e9cc28412Linux >= 2f487712b89376fce267223bbb0db93d393d4b09 < 575faea557f1a184a5f09661bd47ebd3ef3769f8Linux >= 2f487712b89376fce267223bbb0db93d393d4b09 < 3bcf7aca63f0bcd679ae28e9b99823c608e59ce3Linux >= 2f487712b89376fce267223bbb0db93d393d4b09 < a2ea1ef0167d7a84730638d05c20ccdc421b14b6Linux >= 2f487712b89376fce267223bbb0db93d393d4b09 < 1b6f13f626665cac67ba5a012765427680518711Linux >= 2f487712b89376fce267223bbb0db93d393d4b09 < e0bb732eaf77f9ac2f2638bdac9e39b81e0a9682Linux >= 2f487712b89376fce267223bbb0db93d393d4b09 < 48a5fe38772b6f039522469ee6131a67838221a8Linux 4.15Refer to the linked advisories for vendor-supplied fixes and affected version ranges.
Connected by shared product, vendor, weakness, or advisory.
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