CVE-2026-21878

HIGH

BACnet Stack <1.5.0.rc3 - Path Traversal

Title source: llm
STIX 2.1

Description

BACnet Stack is a BACnet open source protocol stack C library for embedded systems. Prior to 1.5.0.rc3, a vulnerability has been discovered in BACnet Stack's file writing functionality where there is no validation of user-provided file paths, allowing attackers to write files to arbitrary directories. This affects apps/readfile/main.c and ports/posix/bacfile-posix.c. This vulnerability is fixed in 1.5.0.rc3.

Scores

CVSS v3 7.5
EPSS 0.0011
EPSS Percentile 28.2%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

CISA SSVC

Vulnrichment
Exploitation poc
Automatable yes
Technical Impact partial

Details

CWE
CWE-22
Status published
Products (1)
bacnetstack/bacnet_stack 1.5.0 rc1 (2 CPE variants)
Published Feb 13, 2026
Tracked Since Feb 18, 2026