CVE-2025-66624

BACnet-stack MS/TP reply matcher OOB read

HIGH
7.5
CVSS Score
Published: December 5, 2025 at 06:36 PM UTC
Updated: June 17, 2026 at 09:57 AM UTC
1 product affected across 1 vendorBacnet Stack

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Severity
HIGH7.5
Exploit prediction
EPSS 0.4%
SSVC
PoC

Description

BACnet Protocol Stack library provides a BACnet application layer, network layer and media access (MAC) layer communications services. Prior to 1.5.0.rc2, The npdu_is_expected_reply function in src/bacnet/npdu.c indexes request_pdu[offset+2/3/5] and reply_pdu[offset+1/2/4] without verifying that those APDU bytes exist. bacnet_npdu_decode() can return offset == 2 for a 2-byte NPDU, so tiny PDUs pass the version check and then get read out of bounds. On ASan/MPU/strict builds this is an immediate crash (DoS). On unprotected builds it is undefined behavior and can mis-route replies; RCE is unlikely because only reads occur, but DoS is reliable.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 1.5.0.rc21.5.0 rc1
Affected range stops below 1.5.0.rc2, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCPoCAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGHGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-125

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