CVE-2025-66624: bacnet stack Out-of-bounds Read

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.

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CVSS v3.1 Score

7.5

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-125 Out-of-bounds Read

Affected Products

Vendor	Product	Versions
bacnetstack	bacnet_stack	All

References

Advisories & Patches

https://github.com/bacnet-stack/bacnet-stack/commit/9378f7d1e70169ebde4a5090bae7603703eadf48 https://github.com/bacnet-stack/bacnet-stack/security/advisories/GHSA-8wgw-5h6x-qgqg

Exploits

https://github.com/bacnet-stack/bacnet-stack/security/advisories/GHSA-8wgw-5h6x-qgqg

Frequently Asked Questions

What is CVE-2025-66624? +

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. It has a CVSS v3.1 base score of 7.5 (HIGH).

How severe is CVE-2025-66624? +

CVE-2025-66624 has a CVSS v3.1 score of 7.5 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching.

What products are affected by CVE-2025-66624? +

CVE-2025-66624 affects products from bacnetstack, specifically: bacnet_stack. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-66624? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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