SEPTEMBER 17, 2026
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Case File

CVE-2026-40279

LOW · CVSS 3.7 EPSS 0.24% Public Exploit

Source: NVD + CISA KEV + EPSS (historical backfill) · Published 2026-04-21 · Last synced 2026-08-04

CyberRota Analysis

This is a low severity vulnerability with a CVSS score of 3.7. Public exploit code or proof-of-concept references have been detected in its references.

Public Exploit Signal

A public exploit, PoC, GitHub repository or Metasploit reference was detected for this CVE.

GitHub PoC Links

Note: these links are listed for security research and verification purposes only.

CVE
CVE-2026-40279
Severity
LOW
CVSS
3.7
EPSS
0.24%

Original NVD Description

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.

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