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CVE-2026-41503

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

HIGH
7.5
CVSS Score
Published: April 24, 2026 at 07:41 PM UTC
Updated: June 17, 2026 at 10:46 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 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.

Affected

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

Bacnet Stack· Bacnetstack
95%
v < 1.4.31.4.0 ≤ v < 1.4.31.5.0 rc1
Affected range stops below 1.4.3, 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:

Patch and advisory references

References (1)

x_refsource_CONFIRMExploitMitigationVendor Advisory
Source: cverecord
https://github.com/bacnet-stack/bacnet-stack/security/advisories/GHSA-5w2v-mwqj-pr2c

SSVC — Action Prioritization

SSVCPoCAutomatablePartial impact

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

CVSS

7.5HIGH[email protected]
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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