# CVE-2026-41502

> Vulnerability · severity: **HIGH** (CVSS 7.5).

## Description

BACnet Stack is a BACnet open source protocol stack C library for embedded systems. Prior to 1.4.3, an off-by-one out-of-bounds read vulnerability in bacnet-stack's ReadPropertyMultiple service decoder allows unauthenticated remote attackers to read one byte past an allocated buffer boundary by sending a crafted RPM request with a truncated object identifier. The vulnerability is in rpm_decode_object_id(), which checks apdu_len < 5 but then accesses all 6 byte positions (indices 0-5) — consuming 1 byte for the context tag, 4 bytes for the object ID, then reading apdu[5] for the opening tag check. A 5-byte input passes the length check but causes a 1-byte OOB read, 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.

## Key facts

- **CVE ID:** CVE-2026-41502
- **Published:** 2026-04-24
- **CVSS severity:** HIGH
- **CVSS base score:** 7.5
- **CWE codes:** CWE-125, CWE-193

## Affected products

- `bacnetstack:bacnet_stack`

## Primary sources

- NIST NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-41502

## Citation

> AI Analytics. CVE-2026-41502. Retrieved 2026-07-19 from https://api.ai-analytics.org/cve/CVE-2026-41502. Derived from NIST NVD. Licensed CC0.

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