Critical 9.1Published Aug 5, 2026

CVE-2026-71263FreeModbus LINUXTCP Port Off-by-One Global Buffer Overflow in xMBPortTCPPool()

Updated under an hour ago (Oct 26, 2026, 6:30 PM ET)

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It affects cwalter-at FreeModbus. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for cwalter-at FreeModbus

Exploited in the last 30 days

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: 9.1 CRITICAL (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
Weakness (CWE): CWE-787
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: TuranSec
NVD analysis: Deferred
Record last updated: Aug 10, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

cwalter-at FreeModbus cwalter_at:freemodbus (from the name)	all versions	CNA record

References

References

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

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.