Vulnerability Details CVE-2026-40279
BACnet Stack is a BACnet open source protocol stack C library for embedded systems. Prior to 1.4.3, decode_signed32() in src/bacnet/bacint.c reconstructs a 32-bit signed integer from four APDU bytes using signed left shifts. When any of the four bytes has bit 7 set (value ≥ 0x80), the left-shift operation overflows a signed int32_t, which is undefined behavior per the C standard. This is flagged thousands of times per minute by UndefinedBehaviorSanitizer on any BACnet input containing signed-integer property values with high-bit-set bytes. This vulnerability is fixed in 1.4.3.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.0
EPSS Ranking 13.4%
CVSS Severity
CVSS v3 Score 3.7
References
Products affected by CVE-2026-40279
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cpe:2.3:a:bacnetstack:bacnet_stack:0.0.1
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cpe:2.3:a:bacnetstack:bacnet_stack:0.0.2
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cpe:2.3:a:bacnetstack:bacnet_stack:0.0.3
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cpe:2.3:a:bacnetstack:bacnet_stack:0.0.4
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cpe:2.3:a:bacnetstack:bacnet_stack:0.0.5
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cpe:2.3:a:bacnetstack:bacnet_stack:0.0.6
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cpe:2.3:a:bacnetstack:bacnet_stack:0.0.7
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cpe:2.3:a:bacnetstack:bacnet_stack:0.0.8
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cpe:2.3:a:bacnetstack:bacnet_stack:0.0.9
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cpe:2.3:a:bacnetstack:bacnet_stack:0.1.0
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cpe:2.3:a:bacnetstack:bacnet_stack:0.1.1
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cpe:2.3:a:bacnetstack:bacnet_stack:0.2.0
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cpe:2.3:a:bacnetstack:bacnet_stack:0.2.1
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cpe:2.3:a:bacnetstack:bacnet_stack:0.2.2
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cpe:2.3:a:bacnetstack:bacnet_stack:0.2.3
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cpe:2.3:a:bacnetstack:bacnet_stack:0.2.4
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cpe:2.3:a:bacnetstack:bacnet_stack:0.2.5
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cpe:2.3:a:bacnetstack:bacnet_stack:0.2.6
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cpe:2.3:a:bacnetstack:bacnet_stack:0.3.0
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cpe:2.3:a:bacnetstack:bacnet_stack:0.3.1
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cpe:2.3:a:bacnetstack:bacnet_stack:0.3.2
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cpe:2.3:a:bacnetstack:bacnet_stack:0.3.3
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cpe:2.3:a:bacnetstack:bacnet_stack:0.3.4
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cpe:2.3:a:bacnetstack:bacnet_stack:0.3.5
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cpe:2.3:a:bacnetstack:bacnet_stack:0.3.6
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cpe:2.3:a:bacnetstack:bacnet_stack:0.4.1
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cpe:2.3:a:bacnetstack:bacnet_stack:0.4.2
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cpe:2.3:a:bacnetstack:bacnet_stack:0.4.3
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cpe:2.3:a:bacnetstack:bacnet_stack:0.4.4
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cpe:2.3:a:bacnetstack:bacnet_stack:0.4.5
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cpe:2.3:a:bacnetstack:bacnet_stack:0.4.6
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cpe:2.3:a:bacnetstack:bacnet_stack:0.4.7
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cpe:2.3:a:bacnetstack:bacnet_stack:0.5.0
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cpe:2.3:a:bacnetstack:bacnet_stack:0.5.1
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cpe:2.3:a:bacnetstack:bacnet_stack:0.5.2
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cpe:2.3:a:bacnetstack:bacnet_stack:0.5.3
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cpe:2.3:a:bacnetstack:bacnet_stack:0.5.4
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cpe:2.3:a:bacnetstack:bacnet_stack:0.5.5
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cpe:2.3:a:bacnetstack:bacnet_stack:0.5.6
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cpe:2.3:a:bacnetstack:bacnet_stack:0.5.7
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cpe:2.3:a:bacnetstack:bacnet_stack:0.5.8
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cpe:2.3:a:bacnetstack:bacnet_stack:0.5.9
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cpe:2.3:a:bacnetstack:bacnet_stack:0.6.0
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cpe:2.3:a:bacnetstack:bacnet_stack:0.6.1
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cpe:2.3:a:bacnetstack:bacnet_stack:0.6.2
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cpe:2.3:a:bacnetstack:bacnet_stack:0.6.3
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cpe:2.3:a:bacnetstack:bacnet_stack:0.6.4
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cpe:2.3:a:bacnetstack:bacnet_stack:0.6.5
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cpe:2.3:a:bacnetstack:bacnet_stack:0.7.3
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cpe:2.3:a:bacnetstack:bacnet_stack:0.7.4
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cpe:2.3:a:bacnetstack:bacnet_stack:0.7.5
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cpe:2.3:a:bacnetstack:bacnet_stack:0.8.1
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cpe:2.3:a:bacnetstack:bacnet_stack:0.8.2
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cpe:2.3:a:bacnetstack:bacnet_stack:0.8.3
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cpe:2.3:a:bacnetstack:bacnet_stack:0.8.4
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cpe:2.3:a:bacnetstack:bacnet_stack:0.8.5
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cpe:2.3:a:bacnetstack:bacnet_stack:0.8.6
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cpe:2.3:a:bacnetstack:bacnet_stack:0.8.7
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cpe:2.3:a:bacnetstack:bacnet_stack:0.9.1
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cpe:2.3:a:bacnetstack:bacnet_stack:1.0.0
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cpe:2.3:a:bacnetstack:bacnet_stack:1.1.0
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cpe:2.3:a:bacnetstack:bacnet_stack:1.1.1
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cpe:2.3:a:bacnetstack:bacnet_stack:1.1.2
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cpe:2.3:a:bacnetstack:bacnet_stack:1.2.0
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cpe:2.3:a:bacnetstack:bacnet_stack:1.3.0
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cpe:2.3:a:bacnetstack:bacnet_stack:1.3.1
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cpe:2.3:a:bacnetstack:bacnet_stack:1.3.2
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cpe:2.3:a:bacnetstack:bacnet_stack:1.3.3
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cpe:2.3:a:bacnetstack:bacnet_stack:1.3.4
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cpe:2.3:a:bacnetstack:bacnet_stack:1.3.5
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cpe:2.3:a:bacnetstack:bacnet_stack:1.3.6
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cpe:2.3:a:bacnetstack:bacnet_stack:1.3.7
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cpe:2.3:a:bacnetstack:bacnet_stack:1.3.8
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cpe:2.3:a:bacnetstack:bacnet_stack:1.4.0
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cpe:2.3:a:bacnetstack:bacnet_stack:1.4.1
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cpe:2.3:a:bacnetstack:bacnet_stack:1.4.2