# CVE-2026-64675: BACnet Stack: Pre-auth OOB read in xy_color_decode (BACnetXYColor) via WriteGroup/WriteProperty

Status: published. Published: 2026-11-13. Updated: 2026-11-13.

BACnet Stack is a BACnet open source protocol stack C library for embedded systems. Prior to versions 1.4.5 and 1.5.1, a single unauthenticated BACnet/IP UDP datagram (port 47808) triggers an out-of-bounds read in xy_color_decode() (src/bacnet/lighting.c), reachable pre-authentication through two default-registered service handlers: the UnconfirmedRequest WriteGroup service (0x0A) and Confirmed WriteProperty on a BACnetXYColor-typed property. This issue has been patched in versions 1.4.5, 1.5.1, and 1.6.0.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- bacnet-stack / bacnet-stack: < 1.4.5 (affected); < 1.5.1 (affected). Source: CNA: GitHub_M

## Severity and prioritization

- CVSS 3.1: 5.3 (medium); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L; source: CNA: GitHub_M

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-125

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/bacnet-stack/bacnet-stack/security/advisories/GHSA-mmg6-p4pr-cj6h (CNA: GitHub_M; x_refsource_CONFIRM)

- https://github.com/bacnet-stack/bacnet-stack/pull/1386 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/bacnet-stack/bacnet-stack/pull/1387 (CNA: GitHub_M; x_refsource_MISC)

## Provenance

- CNA: GitHub_M: https://www.cve.org/CVERecord?id=CVE-2026-64675; retrieved 2026-11-13; source updated 2026-11-13

Revision: f29c372dcdc11c302c3eef0552f9932ba8a002ed4f6fea80aeb22c10c41174ae

Canonical: https://y2.dev/cve/CVE-2026-64675

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