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7.5
BACnet Stack: Unvalidated File Paths Allow Arbitrary File Writing
CVE-2026-21878
Summary
The BACnet Stack library for embedded systems doesn't check file paths, allowing hackers to write files to any directory. This could lead to unauthorized access or data tampering. Update to version 1.5.0.rc3 to fix this issue.
What to do
No fix is available yet. Check with your software vendor for updates.
Affected software
| Vendor | Product | Affected versions | Fix available |
|---|---|---|---|
| bacnetstack | bacnet_stack | 1.5.0 | – |
| bacnetstack | bacnet_stack | 1.5.0 | – |
Original title
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 ...
Original 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.
nvd CVSS3.1
7.5
Vulnerability type
CWE-22
Path Traversal
Published: 13 Feb 2026 · Updated: 10 Mar 2026 · First seen: 6 Mar 2026