CVE-2026-71263 | BDVDB-2026-355652 Detail

cwalter-atFreeModbus

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.

Impact#

Per CVSS v3.1: confidentiality impact none, integrity impact high, availability impact high. Attack vector: network.

Weaknesses#

CWE-787 Out-of-bounds Write

References#

Exploit#

No public exploit known

History#

Version 12026-08-05Record published in the CVE List.
Version 22026-08-10Most recent update recorded in the CVE List.

Published

Published: 2026-08-05
Last modified: 2026-08-10

Vendor information

Vendor: cwalter-at
Product: FreeModbus

All cwalter-at vulnerabilities

Score

9.1 Critical

EPSS

less than 1%, Very Low

Estimated chance of exploitation in the next 30 days. EPSS percentile: 43.2.

KEV

Not listed in the CISA Known Exploited Vulnerabilities catalog.

Impact

Memory Corruption

Action

No specific action is recorded in the source data. Check the references for vendor guidance.

Affected Systems

No version data in the source record.

Scoring System

CVSS v4.0

Not available

CVSS v3.1

9.1 Critical

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

Metric breakdown
Attack Vector	Network
Attack Complexity	Low
Privileges Required	None
User Interaction	None
Scope	Unchanged
Confidentiality	None
Integrity	High
Availability	High

CVSS v3.0

Not available

CVSS v2

Not available

Source: CVE List v5 (record); CISA KEV (kev, action); FIRST EPSS (epss).