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Vulnerability record · CVE-2026-87121 · published 22 September 2026

CVE-2026-87121: Out-of-bounds write vulnerability

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.

9.3 CVSS 4.0 Critical EPSS 0.53% · top 57.6% CWE-787 · Out-of-bounds write Awaiting Analysis
9.3CVSS 4.0 base score
0.53%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
3References
23 Sep 2026Last modified by NVD

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.

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

References

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

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-87121), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.