{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-87121", "assignerOrgId": "7d14cffa-0d7d-4270-9dc0-52cabd5a23a6", "state": "PUBLISHED", "assignerShortName": "icscert", "dateReserved": "2026-09-09T21:28:27.099Z", "datePublished": "2026-09-22T19:48:25.046Z", "dateUpdated": "2026-09-22T20:23:09.069Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "7d14cffa-0d7d-4270-9dc0-52cabd5a23a6", "shortName": "icscert", "dateUpdated": "2026-09-22T19:51:50.077Z"}, "title": "Out-of-bounds write in lwIP TCP/IP Stack MQTT Client Application", "datePublic": "2026-09-22T17:53:00.000Z", "problemTypes": [{"descriptions": [{"lang": "en", "cweId": "CWE-787", "description": "CWE-787", "type": "CWE"}]}], "affected": [{"vendor": "lwIP", "product": "TCP/IP Stack MQTT", "versions": [{"status": "affected", "version": "2.0.1", "lessThanOrEqual": "2.2.1", "versionType": "custom"}], "defaultStatus": "unaffected"}], "descriptions": [{"lang": "en", "value": "lwIP\u00a0TCP/IP Stack MQTT\u00a0is vulnerable to an out-of-bounds write, which may allow an attacker to gain full code execution on the device.", "supportingMedia": [{"type": "text/html", "base64": false, "value": "lwIP&nbsp;TCP/IP Stack MQTT&nbsp;is vulnerable to an out-of-bounds write, which may allow an attacker to gain full code execution on the device."}]}], "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"}}], "solutions": [{"lang": "en", "value": "Users of lwIP are encouraged to update their version of lwIP using the repository found at\u00a0 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": [{"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"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-09-22T20:23:09.069Z"}}]}}