CVE-2026-31662
Last modified
CVE-2026-31662 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. 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. EPSS estimates a 0.39% chance of exploitation in the next 30 days.
Description
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.
Metrics
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness Enumeration
Affected Software
| Vendor | Product | Versions | Update |
|---|---|---|---|
| Linux | Linux Kernel | >= 4.15.1, < 5.10.253 | — |
| Linux | Linux Kernel | >= 5.11, < 5.15.203 | — |
| Linux | Linux Kernel | >= 5.16, < 6.1.169 | — |
| Linux | Linux Kernel | >= 6.2, < 6.6.135 | — |
| Linux | Linux Kernel | >= 6.7, < 6.12.82 | — |
| Linux | Linux Kernel | >= 6.13, < 6.18.23 | — |
| Linux | Linux Kernel | >= 6.19, < 6.19.13 | — |
| Linux | Linux Kernel | 4.15 | — |
| Linux | Linux Kernel | 7.0 | Rc1 |
References
Timeline
- Published
- Last Modified
- Status
- Analyzed
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How Strix Helps
- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
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