Is this vulnerability remotely exploitable?

Yes, in typical BACnet deployments where file operations are exposed over the network, a remote BACnet client that can communicate with the affected service may exploit the issue by sending crafted file path parameters.

What level of access does an attacker need?

The attacker needs network-level access to the BACnet interface that processes file-related requests. No local shell access is required, but the attacker must be able to reach and interact with the BACnet service.

What is the safest general fix pattern?

Constrain all file operations to a predefined directory tree, normalize and canonicalize incoming paths, then verify that the resolved path remains within that tree before opening or writing files. Additionally, reject absolute paths and disallow traversal sequences and unexpected characters according to a strict validation policy.

Severity:

HIGH RISK

(7.5)

Path Traversal (CWE-22) in BACnet Stack File Writing Functionality

CVE-2026-21878

Published:

Feb 13, 2026

Status:

Awaiting Analysis

Summary

Affected Context

Exploit Preconditions

Why This Happens

Potential Impact

General Mitigation Guidance

How Teams Detect Issues Like This

Frequently Asked Questions

Source

NDV

Recent Vulnerabilities

CWE-306

CRITICAL RISK

CRITICAL

(9.8)

Missing Authentication for Forgot-Password Email Change API (CWE-306)

Account Takeover / Loss of Account Control

February 17, 2026

CWE-77;CWE-78

HIGH RISK

HIGH

(7.3)

OS Command Injection (CWE-78) in node-sonos-http-api TTS Provider for macOS

Remote Code Execution on the Server Host

February 17, 2026

Vulnerability Type

Category:

Path Traversal / Directory Traversal

CWE:

CWE-22

Impact:

Arbitrary File Write

Severity:

HIGH RISK

(7.5)

CVSS Version:

3.1

Vulnerability Type

Category:

Path Traversal / Directory Traversal

CWE:

CWE-22

Impact:

Arbitrary File Write

Severity:

HIGH RISK

(7.5)

CVSS Version:

3.1

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Path Traversal (CWE-22) in BACnet Stack File Writing Functionality

Summary

Affected Context

Exploit Preconditions

Why This Happens

Potential Impact

General Mitigation Guidance

How Teams Detect Issues Like This

Frequently Asked Questions

Source

Recent Vulnerabilities

CRITICAL RISK

CRITICAL

(9.8)

Missing Authentication for Forgot-Password Email Change API (CWE-306)

HIGH RISK

HIGH

(7.3)

OS Command Injection (CWE-78) in node-sonos-http-api TTS Provider for macOS

Vulnerability Type

Vulnerability Type

Vulnerability Type

Vulnerability Type

Catch This CVE While Code Is Being Written

Ship clean & secure code faster

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