{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-71254", "assignerOrgId": "309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c", "state": "PUBLISHED", "assignerShortName": "TuranSec", "dateReserved": "2026-08-05T11:43:52.777Z", "datePublished": "2026-08-05T11:44:20.214Z", "dateUpdated": "2026-08-05T12:51:40.361Z"}, "containers": {"cna": {"title": "nanoMODBUS Server-Side Out-of-Bounds Write in handle_read_file_record()", "descriptions": [{"lang": "en", "value": "nanoMODBUS through v1.23.0 contains an out-of-bounds write in the Modbus server-side handle_read_file_record() function (FC 0x14, Read File Record) in nanomodbus.c. The function validates that the total request size does not exceed 245 bytes and that each sub-request's record_length is at most 124, but it never validates the CUMULATIVE response size across all sub-requests before processing them. The accumulator response_data_size is declared as uint8_t and is incremented by 2 + record_length*2 for each of up to 35 sub-requests; with 35 sub-requests of record_length=124, the cumulative demand is 8750 bytes, which overflows the uint8_t accumulator. A subsequent loop then calls get_n(), an internal function with no bounds checking, once per sub-request to obtain a pointer into the 260-byte msg.buf receive buffer and advances the internal buf_idx by up to 248 bytes per call; swap_regs() then writes to that pointer unconditionally. A single crafted FC 0x14 request from an unauthenticated network client can cause up to ~8490 bytes to be written out of bounds past the 260-byte buffer, corrupting adjacent memory in the server process and leading to denial of service or potential remote code execution, particularly on embedded/bare-metal targets without memory protection."}], "problemTypes": [{"descriptions": [{"lang": "en", "description": "CWE-787", "cweId": "CWE-787", "type": "CWE"}]}], "affected": [{"vendor": "debevv", "product": "nanoMODBUS", "programFiles": ["nanomodbus.c"], "versions": [{"version": "0", "lessThanOrEqual": "1.23.0", "status": "affected", "versionType": "semver"}], "defaultStatus": "unaffected"}], "metrics": [{"cvssV3_1": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL"}}], "references": [{"url": "https://github.com/debevv/nanoMODBUS"}, {"url": "https://github.com/debevv/nanoMODBUS/blob/master/nanomodbus.c"}], "credits": [{"lang": "en", "value": "Shukhratbek Uraiimov", "type": "finder"}], "providerMetadata": {"orgId": "309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c", "shortName": "TuranSec", "dateUpdated": "2026-08-05T12:51:40.361Z"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"timestamp": "2026-08-05T12:29:36.579901Z", "id": "CVE-2026-71254", "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": "2026-08-05T12:29:59.671Z"}}]}}

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{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "[0,1.23.0]"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "nanoMODBUS", "source": "cna", "vendor": "debevv"}, "product": "nanomodbus", "vendor": "debevv"}], "created": "2026-08-05T13:30:04.917215+00:00", "updated": "2026-08-05T13:30:04.917242+00:00", "vendors": ["debevv", "debevv$PRODUCT$nanomodbus"]}