CVE-2026-87121

Out-of-bounds write in lwIP TCP/IP Stack MQTT Client Application

State: Published
Severity: 9.3 Critical
Published: Sep 22, 2026
Updated: Sep 22, 2026
Reserved: Sep 9, 2026

Description

lwIP TCP/IP Stack MQTT is vulnerable to an out-of-bounds write, which may allow an attacker to gain full code execution on the device.

Scores

CVSS	Score	Vector	Source
4.0	9.3 Critical	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N	icscert
3.1	9.8 Critical	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H	icscert

Weaknesses

CWE-787

Affected Products

Product	Versions
TCP/IP Stack MQTTlwIP	2.0.1 through 2.2.1Affected

References

https://savannah.nongnu.org/projects/lwip
https://www.cisa.gov/news-events/ics-advisories/icsa-26-265-01
https://github.com/cisagov/CSAF/blob/develop/csaf_files/OT/white/2026/icsa-26-265-01.json

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