CVE-2026-87121
📛 CVE Title
Out-of-bounds write in lwIP TCP/IP Stack MQTT Client Application
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.
Overview
- State
- PUBLISHED
- Assigner (CNA)
- icscert
- CVSS severity
- CRITICAL
- CVSS score
- 9.3 / 10
- 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- Effective score
- 9.3 / 10 CRITICAL source: CNA overview
- CWE(s)
-
CWE-787 - Reserved
- 2026-09-09
- Published
- 2026-09-22 19:48 UTC
- Last updated
- 2026-09-22 20:23 UTC
- Source
- https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/87xxx/CVE-2026-87121.json
- Linked Threat
- CVE-2026-87121 — Out-of-bounds write in lwIP TCP/IP Stack MQTT Client Application
NVD triage scoring NVD CVE 2.0
Layer NVD adds on top of the CNA's CVE record — published / last-modified timestamps, exploitability / impact subscores, and the FIRST.org EPSS probability that this CVE will be exploited in the wild in the next 30 days.
- NVD published
- 2026-09-22 20:17:09 UTC
- NVD last modified
- 2026-09-22 21:17:32 UTC
- NVD CVSS v3.1
- 9.8 / 10 CRITICAL source: ics-cert@hq.dhs.gov
- NVD CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H- Exploitability subscore
- 3.9 / 10
- Impact subscore
- 5.9 / 10
NVD / KEV / EPSS data refreshed 2026-09-23 02:35 UTC. Re-run the 🛰 Backfill from NVD button above to refresh.
European Union Vulnerability Database ENISA EUVD
ENISA's official EU repository for curated vulnerability intelligence. Carries a separate identifier (EUVD-YYYY-NNNN) and frequently exposes an earlier-published description + CVSS than NVD does.
- EUVD ID
-
EUVD-2026-84816 - Assigner
- icscert
- Published
- Sep 22, 2026, 7:48:25 PM
- Updated
- Sep 22, 2026, 8:23:09 PM
- EUVD base score (CVSS 4.0)
-
9.3 / 10
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 - EUVD-reported EPSS
- 0.0000
- Vendors
- lwIP
- Products
-
TCP/IP Stack MQTT (2.0.1 ≤2.2.1)
- Aliases
-
GHSA-h8q6-7rjx-3m2r
ENISA 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.
Affected products (1)
| Vendor | Product | Versions | Platforms |
|---|---|---|---|
| lwIP | TCP/IP Stack MQTT |
2.0.1 (affected)
|
— |
Vendor references (3)
References embedded in the original CVE record by the assigning CNA.
Web references (0)
DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.
No web references attached yet.
NVD-tagged references (3)
Reference list NVD curates from the CNA record, vendor advisories, and third-party reports. The tag chips below are NVD's analyst-assigned categories.
- https://github.com/cisagov/CSAF/blob/develop/csaf_files/OT/white/2026/icsa-26-265-01.json ics-cert@hq.dhs.gov
- https://savannah.nongnu.org/projects/lwip ics-cert@hq.dhs.gov
- https://www.cisa.gov/news-events/ics-advisories/icsa-26-265-01 ics-cert@hq.dhs.gov
Remediations (10)
Remediations are stored against the linked Threat row; the list below is deduplicated across both pages.
-
web:app.opencve.io
An out‑of‑bounds write occurs in the lwIP TCP/IP Stack MQTT client, a flaw that allows a remote adversary to overwrite memory beyond an expected boundary. Exploiting this vulnerability can grant the attacker arbitrary code execution, effectively enabling complete takeover of the affected device and compromising its confidentiality, integrity, and availability.
2026-09-23 15:14 UTC -
web:sec.cloudapps.cisco.com
On September 16, 2026 , the Cisco Product Security Incident Response Team (PSIRT) published the advisories that are listed in the following tables. To remediate these vulnerabilities, Cisco strongly recommends that customers upgrade to the fixed software that is indicated in the advisories. For more information about changes in Cisco PSIRT vulnerability disclosure, see Strengthening the ...
2026-09-23 15:14 UTC -
web:senserva.com
Every Microsoft security patch (KB) and the CVEs it fixes, with severity, CVSS, and CISA KEV status. Cross-linked to the CVE reference.
2026-09-23 15:14 UTC -
web:support.esri.com
This patch deals specifically with the issues listed below under Issues Addressed with this Patch . As part of the patch installation, the Portal for ArcGIS service is stopped and restarted. The restart may take several minutes depending on the number of items on the enterprise deployment. As a best practice, clear the browser cache and re-launch the browser after installing the patch . This ...
2026-09-23 15:14 UTC -
web:support.microsoft.com
Be aware that the update in the Microsoft Download Center applies to the Microsoft Installer (.msi)-based edition of Office 2016. It doesn't apply to the Office 2016 Click-to-Run editions, such as Microsoft Office 365 Home. (See What version of Office am I using?) How to get and install the update Method 1: Microsoft Update This update is available from Microsoft Update. When you turn on ...
2026-09-23 15:14 UTC -
web:support.sap.com
SAP security patch day bulletin This post shares the information on security notes that remediate vulnerabilities discovered in SAP products. SAP strongly recommends that the customer visits the support portal and applies patches on priority to protect their SAP landscape. On 14 th of April 2026 , SAP security patch day saw the release of 19 new security notes. There is 1 update to previously ...
2026-09-23 15:14 UTC -
web:support.sap.com
SAP security Patch Day Bulletin This post shares the information on security notes that remediate vulnerabilities discovered in SAP products. SAP strongly recommends that the customer visits the support portal and applies patches on priority to protect their SAP landscape. On 12 th of May 2026 , SAP security patch day saw the release of 15 new security notes.
2026-09-23 15:14 UTC -
web:www.cisecurity.org
Multiple vulnerabilities have been discovered in Google Android OS, the most severe of which could allow for remote code execution. Android is an operating system developed by Google for mobile devices, including, but not limited to, smartphones, tablets, and watches. Successful exploitation of the most severe of these vulnerabilities could allow for remote code execution. Depending on the ...
2026-09-23 15:14 UTC -
web:www.oracle.com
This Critical Patch Update contains 1448 new security patches across the product families listed below. Please note that a My Oracle Support (MOS) note summarizing the content of this Critical Patch Update and other Oracle Software Security Assurance activities is located at July 2026 Critical Patch Update: Executive Summary and Analysis.
2026-09-23 15:14 UTC -
web:www.tenable.com
The affected product is vulnerable to an out-of-bounds write, which may allow an attacker to gain full code execution on the device.
2026-09-23 15:14 UTC
AI Forensic Analysis
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Raw JSON
The full cvelistV5 record. Download as CVE-2026-87121.json.
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