CVE-2020-36872

HIGH

BACnet Test Server <= 1.01 - Unauthenticated Denial of Service via Malformed BVLC Length Field

Title source: llm
STIX 2.1

Exploitation Summary

EIP tracks 1 public exploit for CVE-2020-36872. PoCs published by LiquidWorm.

AI-analyzed exploit summary This Perl script exploits a denial-of-service vulnerability in BACnet Test Server 1.01 by sending a malformed BVLC Length UDP packet to port 47808, causing the application to crash. The PoC constructs a specific payload (0x81 0x09 0xFF 0xFE) and sends it to the target, triggering an access violation.

Description

BACnet Test Server versions up to and including 1.01 contains a remote denial of service vulnerability in its BACnet/IP BVLC packet handling. The server fails to properly validate the BVLC Length field in incoming UDP BVLC frames on the default BACnet port (47808/udp). A remote unauthenticated attacker can send a malformed BVLC Length value to trigger an access violation and crash the application, resulting in a denial of service.

Exploits (1)

exploitdb WORKING POC
by LiquidWorm · textdoswindows
https://www.exploit-db.com/exploits/48860

This Perl script exploits a denial-of-service vulnerability in BACnet Test Server 1.01 by sending a malformed BVLC Length UDP packet to port 47808, causing the application to crash. The PoC constructs a specific payload (0x81 0x09 0xFF 0xFE) and sends it to the target, triggering an access violation.

Classification
Working Poc 95%
Attack Type
Dos
Complexity
Trivial
Reliability
Reliable
Target: BACnet Test Server 1.01 (BACnet Stack Version 0.5.7)
No auth needed
Prerequisites: Network access to the target on UDP port 47808
devstral-2 · analyzed Feb 16, 2026 Full analysis →

References (6)

Core 6
Core References
Third Party Advisory technical-description exploit
https://www.zeroscience.mk/en/vulnerabilities/ZSL-2020-5597.php
Exploit, Third Party Advisory exploit
https://www.exploit-db.com/exploits/48860
Exploit, Third Party Advisory exploit
https://packetstormsecurity.com/files/159504
Various Sources product
https://www.bac-test.com/

Scores

CVSS v4 8.7
EPSS 0.0045
EPSS Percentile 35.9%
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

CISA SSVC

Vulnrichment
Exploitation poc
Automatable yes
Technical Impact partial

Details

CWE
CWE-400
Status published
Products (1)
BACnet Interoperability Test Services, Inc./BACnet Test Server < 1.01
Published Nov 26, 2025
Tracked Since Feb 18, 2026