{"id":"CVE-2026-71263","published":"2026-08-05T13:24:50.473","lastModified":"2026-08-10T12:17:28.710","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.","cvssScore":9.1,"cvssSeverity":"CRITICAL","cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H","cwes":["CWE-787"],"vendors":[],"products":[],"references":[{"url":"https://github.com/cwalter-at/freemodbus","tags":[]},{"url":"https://github.com/cwalter-at/freemodbus/blob/master/demo/LINUXTCP/port/porttcp.c","tags":[]}],"exploitRefs":[{"url":"https://github.com/cwalter-at/freemodbus","tags":[]},{"url":"https://github.com/cwalter-at/freemodbus/blob/master/demo/LINUXTCP/port/porttcp.c","tags":[]}],"hasPoc":true,"ai":{"summary":"The flaw involves an off-by-one error in the bounds check for LINUXTCP port of FreeModbus, leading to potential buffer overflow. This matters because it can allow attackers to exploit the vulnerability to execute malicious code or cause system crashes.","exploitability":"Exploitation requires specific conditions and is moderately difficult due to the need for precise input manipulation, but once triggered, could lead to severe consequences.","blast_radius":"If exploited, this flaw could result in significant damage, including data corruption, service disruption, or remote code execution on affected systems.","remediation":"Update to the latest version of FreeModbus that addresses the bounds check issue.","tags":["buffer-overflow","ics","modbus","tcp"],"model":"qwen2.5:7b-instruct","analyzedAt":"2026-08-11T06:45:26.634Z"}}