VulnerabilityDeferred

CVE-2026-71263

The LINUXTCP port of FreeModbus contains an off-by-one bounds check in xMBPortTCPPool (demo/LINUXTCP/port/porttcp.c).

CRITICAL 9.1EPSS 0.28%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (0.28%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

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.

CVSS 3.1: 9.1 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
EPSS: 0.28% probability · 20th percentile
CISA KEV: Not listed
Weakness: CWE-787
Source: 309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c

References

https://github.com/cwalter-at/freemodbus
https://github.com/cwalter-at/freemodbus/blob/master/demo/LINUXTCP/port/porttcp.c

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.