{"id":"CVE-2026-87121","state":"PUBLISHED","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.","publishedAt":"2026-09-22T19:48:25.046Z","updatedAt":"2026-09-22T20:23:09.069Z","severity":{"score":9.3,"label":"Critical","version":"4.0","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","source":"icscert"},"assigner":"icscert","products":["lwIP TCP/IP Stack MQTT"],"affected":[{"vendor":"lwIP","product":"TCP/IP Stack MQTT","defaultStatus":"unaffected","versions":[{"version":"2.0.1","status":"affected","lessThanOrEqual":"2.2.1","versionType":"custom"}]}],"references":["https://savannah.nongnu.org/projects/lwip","https://www.cisa.gov/news-events/ics-advisories/icsa-26-265-01","https://github.com/cisagov/CSAF/blob/develop/csaf_files/OT/white/2026/icsa-26-265-01.json"],"weaknesses":["CWE-787"],"ingestedAt":"2026-10-29T20:13:26.108Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/87xxx/CVE-2026-87121.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-87121","state":"PUBLISHED","datePublished":"2026-09-22T19:48:25.046Z","dateUpdated":"2026-09-22T20:23:09.069Z","assignerShortName":"icscert","assignerOrgId":"7d14cffa-0d7d-4270-9dc0-52cabd5a23a6","dateReserved":"2026-09-09T21:28:27.099Z"},"containers":{"cna":{"title":"Out-of-bounds write in lwIP TCP/IP Stack MQTT Client Application","descriptions":[{"lang":"en","value":"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":[{"vendor":"lwIP","product":"TCP/IP Stack MQTT","defaultStatus":"unaffected","versions":[{"version":"2.0.1","status":"affected","lessThanOrEqual":"2.2.1","versionType":"custom"}]}],"references":[{"url":"https://savannah.nongnu.org/projects/lwip"},{"url":"https://www.cisa.gov/news-events/ics-advisories/icsa-26-265-01"},{"url":"https://github.com/cisagov/CSAF/blob/develop/csaf_files/OT/white/2026/icsa-26-265-01.json"}],"metrics":[{"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}],"cvssV3_1":{"version":"3.1","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH","baseSeverity":"CRITICAL","baseScore":9.8,"vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"}},{"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}],"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"HIGH","subConfidentialityImpact":"NONE","vulnIntegrityImpact":"HIGH","subIntegrityImpact":"NONE","vulnAvailabilityImpact":"HIGH","subAvailabilityImpact":"NONE","exploitMaturity":"NOT_DEFINED","Safety":"NOT_DEFINED","Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","valueDensity":"NOT_DEFINED","vulnerabilityResponseEffort":"NOT_DEFINED","providerUrgency":"NOT_DEFINED","version":"4.0","baseSeverity":"CRITICAL","baseScore":9.3,"vectorString":"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"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-787","lang":"en","description":"CWE-787","type":"CWE"}]}],"providerMetadata":{"shortName":"icscert","orgId":"7d14cffa-0d7d-4270-9dc0-52cabd5a23a6","dateUpdated":"2026-09-22T19:51:50.077Z"},"datePublic":"2026-09-22T17:53:00.000Z","solutions":[{"lang":"en","value":"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.","supportingMedia":[{"type":"text/html","base64":false,"value":"Users of lwIP are encouraged to update their version of lwIP using the repository found at&nbsp;<a href=\"https://savannah.nongnu.org/projects/lwip\">https://savannah.nongnu.org/projects/lwip</a>. The commit identifier that contains the fix is f89407ea711879c04d91c92b35d67be78bbaf0f1."}]}],"credits":[{"lang":"en","value":"Shahriyar Jalayeri of ByteRay Ltd. reported this vulnerability to CISA.","type":"finder"}],"source":{"advisory":"ICSA-26-265-01","discovery":"EXTERNAL"},"x_generator":{"engine":"Vulnogram 1.0.5"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-09-22T20:23:00.531481Z","id":"CVE-2026-87121","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-09-22T20:23:09.069Z"}}]}}}