{"id":"CVE-2026-87121","title":"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.","summary":"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.","severity":"critical","cvss":9.8,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","cwe":["CWE-787"],"vendor":"lwIP","product":"TCP/IP Stack MQTT","affected":["tcp_ip_stack_mqtt >= 2.0.1 <= 2.2.1"],"published":"2026-09-22","updated":"2026-09-23","sourceUpdated":"2026-09-23T19:42:48.540","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-87121","references":[{"url":"https://github.com/cisagov/CSAF/blob/develop/csaf_files/OT/white/2026/icsa-26-265-01.json","label":"ics-cert@hq.dhs.gov"},{"url":"https://savannah.nongnu.org/projects/lwip","label":"ics-cert@hq.dhs.gov"},{"url":"https://www.cisa.gov/news-events/ics-advisories/icsa-26-265-01","label":"ics-cert@hq.dhs.gov"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-87121.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-87121"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-87121"}],"tags":["nvd","cve.org","csaf","vex","red-hat"],"epss":0.00775,"epssPercentile":0.55572,"ssvc":{"exploitation":"none","automatable":"yes","technicalImpact":"total","timestamp":"2026-09-22T20:23:00.531481Z"},"ingestedAt":"2026-09-22T20:10:15.095Z","slug":"CVE-2026-87121","body":"## Overview\n\nlwIP 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · updated 2026-10-09 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-87121.json)","depth":"midnight","depthScore":54,"depthScoreParts":{"impact":53.9,"likelihood":0.2,"exploitation":0,"ransomware":0},"changes":[]}