CVE-2026-21878
High
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.
SeverityHigh
CVSS7.5
Exploit probability—
ProductBacnetstack Bacnet Stack
PublishedFeb 13, 2026
First seenFeb 13, 2026
Weakness typeCWE-22Path traversal
How to fix
Sources list no fixed version or patch link for this vulnerability.
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| bacnetstack bacnet_stack | 1.5.0 | — |
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