CVE-2026-31662 Details
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.
A vulnerability in the Linux kernel's TIPC (Transparent Inter-Process Communication) group protocol has been identified. The issue arises in the GRP_ACK_MSG handler, which incorrectly decrements the acknowledgment counter (bc_ackers) for each incoming group acknowledgment. This occurs even when the same member has already acknowledged the current broadcast round. Since bc_ackers is a 16-bit unsigned integer, a duplicate acknowledgment received after the last valid one wraps the counter to 65535. This wraparound leads to an incorrect congestion report, causing subsequent group broadcasts on the affected socket to remain blocked until the group is manually recreated. The vulnerability affects the Linux kernel stable tree.
The vulnerability has been addressed in the Linux kernel. Users should upgrade to the latest version where this issue has been fixed.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
No SSVC data is available for this CVE.
References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://git.kernel.org/stable/c/1b6f13f626665cac67ba5a012765427680518711 | kernel.org | Patch |
| https://git.kernel.org/stable/c/36ec4fdd6250dcd5e73eb09ea92ed92e9cc28412 | kernel.org | Patch |
| https://git.kernel.org/stable/c/3bcf7aca63f0bcd679ae28e9b99823c608e59ce3 | kernel.org | Patch |
| https://git.kernel.org/stable/c/48a5fe38772b6f039522469ee6131a67838221a8 | kernel.org | Patch |
| https://git.kernel.org/stable/c/575faea557f1a184a5f09661bd47ebd3ef3769f8 | kernel.org | Patch |
| https://git.kernel.org/stable/c/a2ea1ef0167d7a84730638d05c20ccdc421b14b6 | kernel.org | Patch |
| https://git.kernel.org/stable/c/a7db57ccca21f5801609065473c89a38229ecb92 | kernel.org | Patch |
| https://git.kernel.org/stable/c/e0bb732eaf77f9ac2f2638bdac9e39b81e0a9682 | kernel.org | Patch |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-191 | Integer Underflow (Wrap or Wraparound) | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| linux linux kernel | >= 4.15.1, < 5.10.253 >= 5.11, < 5.15.203 >= 5.16, < 6.1.169 >= 6.2, < 6.6.135 >= 6.7, < 6.12.82 >= 6.13, < 6.18.23 >= 6.19, < 6.19.13 4.15 - 7.0 rc1 7.0 rc2 7.0 rc3 7.0 rc4 7.0 rc5 7.0 rc6 7.0 rc7 |
CPE
Remediation
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Change History
4 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jun 17, 2026 | CVE Modified | kernel.org |
| Apr 27, 2026 | Initial Analysis | [email protected] |
| Apr 27, 2026 | CVE Modified | kernel.org |
| Apr 24, 2026 | New CVE Received | kernel.org |