by Kastro
Paper/Archive/CVE-2026-87121

CVE-2026-87121

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

EPSS 0.8%CVSS 9.8
critical.is priorityof 100
41
CVSS 9.8 (CNA)9.8 / 10 × 3029.4Not in CISA KEV+300.0EPSS percentile 55.8.558 × 2011.2No public exploit+100.0SSVC exploitation: none+100.0
Description · from the CVE record

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.

Affected

ProductAffectedFixed inSource
TCP/IP Stack MQTT2.0.1 – 2.2.1–CNA

Scores by source

icscert (CNA)9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
icscert (CNA)9.3CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
CISA ADPSSVCExploitation: none · Automatable: yes · Technical impact: total

References

refsavannah.nongnu.org/projects/lwiprefcisa.gov/news-events/ics-advisories/icsa-26-265-01refgithub.com/cisagov/CSAF/blob/develop/csaf_files/OT/white/2026/icsa-26-265-01.json