CVE-2026-87121CWE-787

CVE-2026-87121

Critical · published September 23, 2026

CVSS v3.1
9.8
EPSS
1%
Percentile
43.8
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
9.8 · CRITICAL
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS v4.0
9.3 · 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
EPSS
0.00528 · 43.8th percentile
Weakness
CWE-787 · Out-of-bounds Write
Published
2026-09-23T00:17Z
References (3)
https://github.com/cisagov/CSAF/blob/develop/csaf_files/OT/white/2026/icsa-26-265-01.json · [email protected]https://savannah.nongnu.org/projects/lwip · [email protected]https://www.cisa.gov/news-events/ics-advisories/icsa-26-265-01 · [email protected]
EPSS history
Timeline
  • 24 SEP 03:25Z
    EPSS moved — → 1%
    epss
  • 22 SEP 19:48Z
    Out-of-bounds write in lwIP TCP/IP Stack MQTT Client Application
    cvelistv5