CVE-2026-40279

LOW EPSS 15.3%
Published Apr 21, 20262mo ago · Modified Jun 17, 20262w ago
3.7 CVSS 3.1
Low
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Published Apr 21, 2026 2mo ago
Last Modified Jun 17, 2026 2w ago

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.

CVSS Details

Base Score
3.7
Exploitability
2.2
Impact
1.4
Vector string
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
Attack Vector Network
Attack Complexity High
Privileges Required None
User Interaction None
Scope Unchanged
Confidentiality None
Integrity None
Availability Low

Threat Intelligence

EPSS Exploit Probability
15.3% percentile
Exploit & Patch Status
Public Exploit Known
No Patch Available

Weaknesses 1

CWE-758

Affected Products 1

VendorProductVersionRange
bacnetstackbacnet_stack* <1.4.3

References 1

  • github.com https://github.com/bacnet-stack/bacnet-stack/security/advisories/GHSA-326g-j95f-gmxv
    ExploitMitigationVendor Advisory

Remediation

No remediation data recorded yet

Check vendor advisories and the NVD entry for patch availability.