CVE-2026-46676: BACnet Stack: Uninitialized Value Use in AtomicReadFile-ACK Record-Access Encoder Causes Response Corruption and Conditional Information Disclosure
BACnet Stack is a BACnet open source protocol stack C library for embedded systems. From versions 1.4.0 to before 1.4.4, and 1.5.0 to before 1.5.1, an uninitialized value use vulnerability in bacnet-stack's AtomicReadFile record-access ACK encoder allows unauthenticated remote attackers to corrupt the encoded OCTET STRING length and payload boundary in network responses by sending a crafted AtomicReadFile request that reaches a successful record-access path. This issue has been patched in versions 1.4.4 and 1.5.1.
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
BACnet Stackto a version that resolves this vulnerability.Fixed in 1.4.4 - Upgrade
Upgrade
BACnet Stackto a version that resolves this vulnerability.Fixed in 1.5.1
Event History
Frequently Asked Questions
Which deployments are affected?
BACnet Stack versions 1.4.0 through 1.4.3 and 1.5.0 are affected. Versions 1.4.4 and 1.5.1 contain the fix.
What must an attacker do to trigger the issue?
An unauthenticated remote attacker must send a crafted AtomicReadFile request that reaches a successful record-access path. The flaw affects encoding of the resulting AtomicReadFile-ACK response.
What is the likely security impact?
The malformed response can have a corrupted OCTET STRING length and payload boundary, creating a conditional information-disclosure risk. The provided severity assessment rates confidentiality impact as low and integrity and availability impact as none.