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Wed, 05 Aug 2026 14:30:00 +0000
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ssvc
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Wed, 05 Aug 2026 13:45:00 +0000
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Debevv
Debevv nanomodbus |
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Debevv
Debevv nanomodbus |
Wed, 05 Aug 2026 13:15:00 +0000
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cvssV3_1
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cvssV3_1
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Wed, 05 Aug 2026 12:00:00 +0000
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| Description | 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. | |
| Title | nanoMODBUS Server-Side Out-of-Bounds Write in handle_read_file_record() | |
| Weaknesses | CWE-787 | |
| References |
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| Metrics |
cvssV3_1
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Projects
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Status: PUBLISHED
Assigner: TuranSec
Published:
Updated: 2026-08-05T12:51:40.361Z
Reserved: 2026-08-05T11:43:52.777Z
Link: CVE-2026-71254
Updated: 2026-08-05T12:29:55.464Z
No data.
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OpenCVE Enrichment
Updated: 2026-08-05T15:00:05Z