🔐 CVE Alert

CVE-2026-87121

CRITICAL 9.8

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

CVSS Score
9.8
EPSS Score
0.0%
EPSS Percentile
0th

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.

CWE CWE-787
Vendor lwip
Product tcp/ip stack mqtt
Published Sep 22, 2026
Last Updated Sep 22, 2026
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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Affected Versions

lwIP / TCP/IP Stack MQTT
2.0.1 ≤ 2.2.1

References

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

Credits

Shahriyar Jalayeri of ByteRay Ltd. reported this vulnerability to CISA.