CVE-2026-21870

5.5 MEDIUM
Published: February 13, 2026 Modified: February 18, 2026
View on NVD

Description

BACnet Protocol Stack library provides a BACnet application layer, network layer and media access (MAC) layer communications services. In 1.4.2, 1.5.0.rc2, and earlier, an off-by-one stack-based buffer overflow in the ubasic interpreter causes a crash (SIGABRT) when processing string literals longer than the buffer limit. The tokenizer_string function in src/bacnet/basic/program/ubasic/tokenizer.c incorrectly handles null termination for maximum-length strings. It writes a null byte to dest[40] when the buffer size is only 40 (indices 0-39), triggering a stack overflow.

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CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory

3 reference(s) from NVD

Quick Stats

CVSS v3 Score
5.5 / 10.0
EPSS (Exploit Probability)
0.0%
0th percentile
Exploitation Status
Not in CISA KEV

Weaknesses (CWE)

Affected Vendors

bacnetstack