CVE-2026-71263
FreeModbus LINUXTCP Port Off-by-One Global Buffer Overflow in xMBPortTCPPool()
- State
- Published
- Severity
- 9.1 Critical
- Published
- Aug 5, 2026
- Updated
- Aug 10, 2026
- Reserved
- Aug 5, 2026
Description
The LINUXTCP port of FreeModbus contains an off-by-one bounds check in xMBPortTCPPool (demo/LINUXTCP/port/porttcp.c). The check uses a strict greater-than comparison instead of greater-than-or-equal against the 263-byte MB_TCP_BUF_SIZE limit.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 9.1 Critical | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H | TuranSec |
Weaknesses
Affected Products
| Product | Versions |
|---|---|
FreeModbuscwalter-at |
|
References
- https://github.com/cwalter-at/freemodbusthird-party-advisory
- https://github.com/cwalter-at/freemodbus/blob/master/demo/LINUXTCP/port/porttcp.cthird-party-advisory
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