lwIP TCP/IP Stack MQTT Client Application

CCISA Advisories · 5 hours ago

View CSAF Summary Successful exploitation of this vulnerability could allow an attacker to gain full code execution on the device. The following versions of lwIP TCP/IP Stack MQTT Client Application are affected: MQTT Client Application >=2.0.1|<=2.2.1 (CVE-2026-87121) CVSS Vendor Equipment Vulnerabilities v3 9.8 lwIP lwIP TCP/IP Stack MQTT Client Application Out-of-bounds Write Background Critical Infrastructure Sectors: Chemical, Communications, Critical Manufacturing, Energy, Financial Services, Healthcare and Public Health, Transportation Systems, Water and Wastewater Systems Countries/Areas Deployed: Worldwide Company Headquarters Location: Sweden Vulnerabilities Expand All + CVE-2026-87121 The affected product is vulnerable to an out-of-bounds write, which may allow an attacker to gain full code execution on the device. View CVE Details Affected Products lwIP TCP/IP Stack MQTT Client Application Vendor:lwIP Product Version:lwIP MQTT Client Application: >=2.0.1|<=2.2.1 Product Status:known_affected Remediations MitigationUsers 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.  Relevant CWE: CWE-787 Out-of-bounds Write Metrics CVSS Version Base Score Base Severity Vector String 3.1 9.8 CRITICAL CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H 4.0 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 Acknowledgments Shahriyar Jalayeri of ByteRay Ltd. reported this vulnerability to CISA. Legal Notice and Terms of Use This product is provided subject to this Notification (https://www.cisa.gov/notification) and this Privacy & Use policy (https://www.cisa.gov/privacy-policy). Recommended Practices CISA recommends users take defensive measures to minimize the risk of exploitation of this vulnerability. Minimize network exposure for all control system devices and/or systems, ensuring they are not accessible from the internet. Locate control system networks and remote devices behind firewalls and isolating them from business networks. When remote access is required, use more secure methods, such as Virtual Private Networks (VPNs), recognizing VPNs may have vulnerabilities and should be updated to the most current version available. Also recognize VPN is only as secure as the connected devices. CISA reminds organizations to perform proper impact analysis and risk assessment prior to deploying defensive measures. CISA also provides a section for control systems security recommended practices on the ICS webpage on cisa.gov/ics. Several CISA products detailing cyber defense best practices are available for reading and download, including Improving Industrial Control Systems Cybersecurity with Defense-in-Depth Strategies. CISA encourages organizations to implement recommended cybersecurity strategies for proactive defense of ICS assets. Additional mitigation guidance and recommended practices are publicly available on the ICS webpage at cisa.gov/ics in the technical information paper, ICS-TIP-12-146-01B--Targeted Cyber Intrusion Detection and Mitigation Strategies. Organizations observing suspected malicious activity should follow established internal procedures and report findings to CISA for tracking and correlation against other incidents. CISA also recommends users take the following measures to protect themselves from social engineering attacks: Do not click web links or open attachments in unsolicited email messages. Refer to Recognizing and Avoiding Email Scams for more information on avoiding email scams. Refer to Avoiding Social Engineering and Phishing Attacks for more information on social engineering attacks. No known public exploitation specifically targeting this vulnerability has been reported to CISA at this time. Revision History Initial Release Date: 2026-09-22 Date Revision Summary 2026-09-22 1 Initial Publication Legal Notice and Terms of Use