CVE-2026-41475: BACnet Stack: Out-of-Bounds Read in WritePropertyMultiple Decoder via Deprecated Tag Parser

Severity: critical (CVSS 9.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-04-24 · updated 2026-06-17
Weakness: CWE-125

Description

BACnet Stack is a BACnet open source protocol stack C library for embedded systems. Prior to 1.4.3, an out-of-bounds read vulnerability in bacnet-stack's WritePropertyMultiple service decoder allows unauthenticated remote attackers to read past allocated buffer boundaries by sending a truncated WPM request. The vulnerability stems from wpm_decode_object_property() calling the deprecated decode_tag_number_and_value() function, which performs no bounds checking on the input buffer. A crafted BACnet/IP packet with a truncated property payload causes the decoder to read 1-7 bytes past the end of the buffer, leading to crashes or information disclosure on embedded BACnet devices. This vulnerability is fixed in 1.4.3.

Affected products

bacnet-stack: from 1.4.0 before 1.4.3; 1.5.0-rc1, 1.5.0-rc2, 1.5.0-rc3 — fixed in 1.4.3

How to fix

Upgrade to a fixed version: bacnet-stack 1.4.3. Check the vendor advisory for mitigations.

References

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