Read the docs
TI-2026-30089 Aliases CVE-2026-41503

BACnet Stack: Out-of-Bounds Read in ReadPropertyMultiple Property Decoder via Deprecated Tag Parser

Priority HIGH 77CWE-125Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-125 and the CVSS impact.

Summary

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 ReadPropertyMultiple service property decoder allows unauthenticated remote attackers to read past allocated buffer boundaries by sending an RPM request with a truncated property list. The vulnerability stems from rpm_decode_object_property() calling the deprecated decode_tag_number_and_value() function at src/bacnet/rpm.c:344, which accepts no buffer length parameter and reads blindly from whatever pointer it receives. A crafted BACnet/IP packet with a 1-byte property payload containing an extended tag marker (0xF9) causes the decoder to read 1 byte past the end of the buffer, leading to crashes on embedded BACnet devices. The vulnerability exists in src/bacnet/rpm.c and affects any deployment that enables the ReadPropertyMultiple confirmed service handler (enabled by default in the reference server). This vulnerability is fixed in 1.4.3.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00415 36th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed bacnet-stack (bacnet-stack): 1.4.3

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
bacnet-stackbacnet-stack1.4.0 to before 1.4.31.4.3Patch availableCNA
  • bacnet-stack Vendorbacnet-stack Affected 1.4.0 to before 1.4.3 Fixed in 1.4.3 Patch available CNA

CPE configurations NVD · 2

CPEVersionsRoleVendor
cpe:2.3:a:bacnetstack:bacnet_stack:*:*:*:*:*:*:*:*1.4.0 to before 1.4.3Vulnerablebacnet-stack
cpe:2.3:a:bacnetstack:bacnet_stack:1.5.0:rc1:*:*:*:*:*:*1.5.0 rc1Vulnerablebacnet-stack
  • cpe:2.3:a:bacnetstack:bacnet_stack:*:*:*:*:*:*:*:* Versions 1.4.0 to before 1.4.3 Vulnerable ·bacnet-stack
  • cpe:2.3:a:bacnetstack:bacnet_stack:1.5.0:rc1:*:*:*:*:*:* Versions 1.5.0 rc1 Vulnerable ·bacnet-stack

Remediation

  • Fix · CNA bacnet-stack (bacnet-stack) Fixed in 1.4.3

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-41503

References

Exploit 1

  • TI-2026-30088 BACnet Stack: Off-by-One Out-of-Bounds Read in ReadPropertyMultiple Object ID Decoder CVSS 4.0HIGH 8.7
  • TI-2026-30063 BACnet Stack: Out-of-Bounds Read in WritePropertyMultiple Decoder via Deprecated Tag Parser CVSS 4.0HIGH 8.7
  • TI-2026-21234 BACnet Stack WriteProperty decoding length underflow leads to OOB read and crash CVSS 4.0HIGH 7.8
  • TI-2026-17579 BACnet Stack Improperly Limits Pathnames to a Restricted Directory CVSS 3.1HIGH 7.5
  • TI-2025-41018 BACnet-stack MS/TP reply matcher OOB read CVSS 3.1HIGH 7.5
  • TI-2026-29061 BACnet Stack: Undefined-behavior signed left shift in `decode_signed32()` CVSS 3.1LOW 3.7
See all 8 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences