# CVE-2026-52786: BACnet Stack: malicious ReadPropertyMultiple-ACK with excessive properties causes global-buffer-overflow in ProcessRPMData()

Status: published. Published: 2026-11-12. Updated: 2026-11-12.

BACnet Stack is a BACnet open source protocol stack C library for embedded systems. Prior to versions 1.4.5, 1.5.1, and 1.6.0, in the official apps/epics client tool on v1.6.0-rc1 (not in the generic BACnet RPM ACK decoder alone) a malicious BACnet/IP endpoint can reply to the EPICS tool’s legitimate ReadPropertyMultiple request with a syntactically valid ReadPropertyMultiple-ACK that contains more heading properties than the tool’s fixed local storage can hold. The response is decoded successfully and later consumed by ProcessRPMData(), which writes property values into a fixed global array using an unbounded linear index. This results in a reproducible global-buffer-overflow in apps/epics/main.c. This is a network-reachable memory corruption in the official epics tool’s response-processing path. The root cause is that apps/epics treats a remotely supplied variable-length RPM property list as if it were a trusted, fixed-size local heading-property set. 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); < 1.6.0 (affected). Source: CNA: GitHub_M

## Severity and prioritization

- CVSS 3.1: 7.1 (high); CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:H; source: CNA: GitHub_M

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-129, CWE-787

## 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-c4q6-7827-mfg6 (CNA: GitHub_M; x_refsource_CONFIRM)

- https://github.com/bacnet-stack/bacnet-stack/pull/1366 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/bacnet-stack/bacnet-stack/pull/1409 (CNA: GitHub_M; x_refsource_MISC)

## Provenance

- CNA: GitHub_M: https://www.cve.org/CVERecord?id=CVE-2026-52786; retrieved 2026-11-12; source updated 2026-11-12

Revision: f86dc2cec3b3bdefe14d876340c8a0668ff39831732180128d43adcdf7f2f940

Canonical: https://y2.dev/cve/CVE-2026-52786

## Agent and API access

Public CVE pages, Markdown, and JSON are free to read without an account or API key.

- Public catalog: https://y2.dev/cve/index.json. Follow nextCursor with the same search, filters, sort, and limit (1–100). A null cursor marks the end.

- WebMCP: search_cve_disclosures, get_cve_disclosure, get_cve_page_markdown, get_y2_cve_access. Available in compatible browsers.

- Cyber API: https://api.y2.dev/api/v2/cyber/cves and https://api.y2.dev/api/v2/cyber/cves/{cveId}.

- Y2 Pro or Elite: create a workspace API key with the intel:cyber scope and send Authorization: Bearer <Y2_API_KEY>. Setup: https://y2.dev/docs/api/create-key.

- x402: Pay per request without an account or API key. Omit Authorization, read the HTTP 402 PAYMENT-REQUIRED challenge, validate its current requirements, and retry with PAYMENT-SIGNATURE through an authorized payment client. These browser tools never make payments. Guide: https://y2.dev/docs/api/x402.

- OpenAPI: https://y2.dev/api/openapi.yaml. Agent access metadata: https://y2.dev/cve/agent.json.

Collected public records only. Check source status for coverage and freshness.