Critical 9.8Published Sep 22, 2026

CVE-2026-87121Out-of-bounds write in lwIP TCP/IP Stack MQTT Client Application

Updated under an hour ago (2026-10-19 09:00 UTC)

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It affects lwIP TCP/IP Stack MQTT. 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 lwIP TCP/IP Stack MQTT

Exploited in the last 30 days

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.

CVSS: 9.8 CRITICAL (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/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: icscert
NVD analysis: Awaiting Analysis
Record last updated: Sep 22, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

lwIP TCP/IP Stack MQTT lwip:tcp_ip_stack_mqtt (from the name)	from 2.0.1 through 2.2.1	CNA record

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

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.