CVE-2026-87121 PUBLISHED

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

Assigner: icscert
Reserved: 09.09.2026 Published: 22.09.2026 Updated: 22.09.2026

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 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS Score: 9.8

Attack Vector	Network	Scope	Unchanged
Attack Complexity	Low	Confidentiality Impact	High
Privileges Required	None	Integrity Impact	High
User Interaction	None	Availability Impact	High

CVSS 3.1

CVSS Vector: 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
CVSS Score: 9.3

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Network	Confidentiality	High	Confidentiality	None
Attack Complexity	Low	Integrity	High	Integrity	None
Attack Requirements	None	Availability	High	Availability	None
Privileges Required	None
User Interaction	None

CVSS 4.0

Product Status

Vendor	lwIP
Product	TCP/IP Stack MQTT
Versions	Default: unaffected affected from 2.0.1 to 2.2.1 (incl.)

Solutions

Users of lwIP are encouraged to update their version of lwIP using the repository found at https://savannah.nongnu.org/projects/lwip . The commit identifier that contains the fix is f89407ea711879c04d91c92b35d67be78bbaf0f1.

CVE-2026-87121 PUBLISHED

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

Metrics

Product Status

Solutions

Credits

References

Problem Types