CVE-2026-71263 Detail
Received
This CVE record has recently been published to the CVE List and has been included within the NVD dataset. DescriptionThe LINUXTCP port of FreeModbus contains an off-by-one bounds check in xMBPortTCPPool() (demo/LINUXTCP/port/porttcp.c). The check `if (usTCPFrameBytesLeft > MB_TCP_BUF_SIZE)` uses a strict greater-than comparison instead of greater-than-or-equal against the 263-byte MB_TCP_BUF_SIZE limit. An MBAP frame with a Length field of 264 makes usTCPFrameBytesLeft equal to 263, which passes the flawed check, and the subsequent recv() call writes up to 263 bytes starting at buffer offset 7 into the 263-byte static buffer aucTCPBuf, overflowing it by 7 bytes into the adjacent static variable usTCPBufPos. A single crafted, unauthenticated Modbus TCP packet triggers the overflow, since Modbus has no built-in authentication. Metrics
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CVSS 4.0 Severity and Vector Strings:
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Weakness Enumeration
Quick InfoCVE Dictionary Entry:CVE-2026-71263 NVD Published Date: 08/05/2026 NVD Last Modified: 08/05/2026 Source: TuranSec |
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