{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-71263","assignerOrgId":"309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c","state":"PUBLISHED","assignerShortName":"TuranSec","dateReserved":"2026-08-05T12:23:34.966Z","datePublished":"2026-08-05T12:26:11.423Z","dateUpdated":"2026-08-10T11:46:28.356Z"},"containers":{"cna":{"title":"FreeModbus LINUXTCP Port Off-by-One Global Buffer Overflow in xMBPortTCPPool()","descriptions":[{"lang":"en","value":"The LINUXTCP port of FreeModbus contains an off-by-one bounds check in xMBPortTCPPool (demo/LINUXTCP/port/porttcp.c). The check uses a strict greater-than comparison instead of greater-than-or-equal against the 263-byte MB_TCP_BUF_SIZE limit.","supportingMedia":[{"type":"text/html","base64":false,"value":"<p>The LINUXTCP port of FreeModbus contains an off-by-one bounds check in xMBPortTCPPool (demo/LINUXTCP/port/porttcp.c). The check uses a strict greater-than comparison instead of greater-than-or-equal against the 263-byte MB_TCP_BUF_SIZE limit.</p>"}]}],"problemTypes":[{"descriptions":[{"lang":"en","description":"CWE-787","cweId":"CWE-787","type":"CWE"}]}],"affected":[{"vendor":"cwalter-at","product":"FreeModbus","programFiles":["demo/LINUXTCP/port/porttcp.c"],"versions":[{"version":"0","lessThanOrEqual":"*","status":"affected","versionType":"custom"}],"defaultStatus":"unaffected"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H","baseScore":9.1,"baseSeverity":"CRITICAL","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"HIGH","availabilityImpact":"HIGH"}}],"references":[{"url":"https://github.com/cwalter-at/freemodbus","tags":["third-party-advisory"]},{"url":"https://github.com/cwalter-at/freemodbus/blob/master/demo/LINUXTCP/port/porttcp.c","tags":["third-party-advisory"]}],"credits":[{"lang":"en","value":"Alibek Baxtiyorov","type":"finder"}],"providerMetadata":{"orgId":"309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c","shortName":"TuranSec","dateUpdated":"2026-08-10T11:46:28.356Z"},"source":{"discovery":"EXTERNAL"},"datePublic":"2026-08-05T12:26:11.423Z"},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-08-05T15:39:27.280961Z","id":"CVE-2026-71263","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-08-05T15:39:36.370Z"}}]}}