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CVE-2026-41503

Bacnetstack Bacnet Stack out-of-bounds read

7.5 HIGHPublic exploitEPSS 0.60%
  1. Published24 Apr 2026

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.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityNone
IntegrityNone
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

Bacnetstack Bacnet Stack≥ 1.4.0 < 1.4.3 · 1.5.0

Remediation

Fixed in
Bacnetstack Bacnet Stack≥ 1.4.3

References

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Frequently asked

Is CVE-2026-41503 being actively exploited?

CVE-2026-41503 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 0.60%.

How severe is CVE-2026-41503?

CVE-2026-41503 has a CVSS 3.1 base score of 7.5, rated high. EPSS estimates a 0.60% probability of exploitation.

Which products are affected by CVE-2026-41503?

Affected products include Bacnetstack Bacnet Stack.

How do I fix CVE-2026-41503?

Upgrade affected software to a fixed version, for example Bacnetstack Bacnet Stack 1.4.3 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.