Out-of-bounds write in lwIP TCP/IP Stack MQTT Client Application
Summary
| CVE | CVE-2026-87121 |
|---|---|
| State | PUBLISHED |
| Assigner | icscert |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-09-22 20:17:09 UTC |
| Updated | 2026-09-23 19:42:48 UTC |
| 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. |
Risk And Classification
Primary CVSS: v4.0 9.3 CRITICAL from [email protected]
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:X/V:X/RE:X/U:X
EPSS: 0.005280000 probability, percentile 0.421860000 (date 2026-09-24)
Problem Types: CWE-787 | CWE-787 CWE-787
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | [email protected] | Secondary | 9.3 | CRITICAL | 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/C... |
| 4.0 | CNA | CVSS | 9.3 | CRITICAL | 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 |
| 3.1 | [email protected] | Secondary | 9.8 | CRITICAL | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | CNA | CVSS | 9.8 | CRITICAL | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
CVSS v4.0 Breakdown
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:X/V:X/RE:X/U:X
CVSS v3.1 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | LwIP | TCP/IP Stack MQTT | affected 2.0.1 2.2.1 custom | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| savannah.nongnu.org/projects/lwip | [email protected] | savannah.nongnu.org | |
| www.cisa.gov/news-events/ics-advisories/icsa-26-265-01 | [email protected] | www.cisa.gov | |
| github.com/cisagov/CSAF/blob/develop/csaf_files/OT/white/2026/icsa-26-26... | [email protected] | github.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Shahriyar Jalayeri of ByteRay Ltd. reported this vulnerability to CISA. (en)
Additional Advisory Data
Solutions
CNA: 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.