CVE
BACnet Stack global buffer overflow in ProcessRPMData()
Affects the official apps/epics client tool in bacnet-stack v1.6.0-rc1 or earlier, when it sends its heading-property ReadPropertyMultiple request to a malicious responder. Fixed in 1.4.5, 1.5.1, and 1.6.0.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in 1.4.5, 1.5.1, 1.6.0
- Who is exposed
- Specific setups only
Do first: Check whether your setup matches what the bug needs. Official apps/epics client tool in bacnet-stack v1.6.0-rc1 or earlier; the generic RPM ACK decoder alone is not the issue The EPICS tool has sent its legitimate ReadPropertyMultiple request for heading properties to the malicious responder
- Last modified
- Whether it needs action now or is a reference record, by fixed rules, with why. Last checked is when cve.now last re-read it.What do these mean? →
- Reference
- Last checked
- FIRST's estimate of the chance attackers exploit it in the next 30 days, updated daily.What do these mean? →
- 0.22% · 12th percentile
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 19/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
BACnet Stack's official epics client tool has a memory corruption flaw in how it processes responses from remote devices. A malicious BACnet/IP device on the network can send a crafted ReadPropertyMultiple-ACK reply, without logging in, after the tool sends a read request, which overflows a fixed global buffer and corrupts memory.
Read the original description
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.
Who should check
Teams running the apps/epics EPICS client tool from bacnet-stack v1.6.0-rc1 or earlier to query BACnet/IP devices, including any tool pointed at untrusted endpoints.
Read the source excerpt
“The issue is in the official apps/epics client tool on v1.6.0-rc1”
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure12/25Specific setups only, reachable over the network without a login
- Reach?/20Unknown. No tracked technology or package matched
- Severity7.1/10CVSS 7.1
- No patch0/5No signal
What would change the score
- Would score about 69 if added to CISA KEV
- Would score about 64 if CISA's SSVC rates exploitation active
What to do
Check whether your setup matches what the bug needs.
Official apps/epics client tool in bacnet-stack v1.6.0-rc1 or earlier; the generic RPM ACK decoder alone is not the issue The EPICS tool has sent its legitimate ReadPropertyMultiple request for heading properties to the malicious responderUpgrade to a fixed version: 1.4.5, 1.5.1, 1.6.0.
Check your systems with an agent
Paste this into a coding or ops agent. It checks your systems read-only and reports a table per asset.
Check whether my systems are affected by CVE-2026-52786 (BACnet Stack: malicious ReadPropertyMultiple-ACK with excessive properties causes global-buffer-overflow in ProcessRPMData()), using the cve.now data below.
Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only.
What cve.now has for CVE-2026-52786 (entry last updated 2026-11-12):
Affected:
- bacnet-stack bacnet-stack: fixed in 1.4.5; fixed in 1.5.1; fixed in 1.6.0
Fixed versions: 1.4.5, 1.5.1, 1.6.0.
Conditions (all must be true for the bug to be hit):
- Official apps/epics client tool in bacnet-stack v1.6.0-rc1 or earlier; the generic RPM ACK decoder alone is not the issue (source: https://github.com/bacnet-stack/bacnet-stack/security/advisories/GHSA-c4q6-7827-mfg6)
- The EPICS tool has sent its legitimate ReadPropertyMultiple request for heading properties to the malicious responder (source: https://github.com/bacnet-stack/bacnet-stack/security/advisories/GHSA-c4q6-7827-mfg6)
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
Attacker needs: network access, no login, a user action.
CISA KEV: CVE-2026-52786 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-52786 only. If you also check another CVE, look up its own KEV status; never assume it from this one.
How to check:
- Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory.
Verify against the linked advisories before concluding, and cite the date you read each one:
- https://github.com/bacnet-stack/bacnet-stack/security/advisories/GHSA-c4q6-7827-mfg6
- https://github.com/bacnet-stack/bacnet-stack/pull/1366
- https://github.com/bacnet-stack/bacnet-stack/pull/1409
Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing.
Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action.
Entry: https://cve.now/CVE-2026-52786
For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example execute with name cve.get and arguments {"id": "CVE-2026-52786"}.Timeline
- CVE published
- First seen by cve.now
Affected versions
- bacnet-stack bacnet-stack
fixed in 1.4.5; fixed in 1.5.1; fixed in 1.6.0
Evidence 5
Vendor advisory · 1
Establishes: Affected and fixed versions.
- Advisory
CVE record · 2
Establishes: The identifier and description.
- Record
- Record
Other links · 2
- Repository
- Repository
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-52786
Is CVE-2026-52786 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
A malicious BACnet/IP endpoint can crash the EPICS client, causing a denial of service, through an out-of-bounds write to global memory triggered by a ReadPropertyMultiple acknowledgement with excessive properties. Code execution is not proven.Source: github.com
Which versions are affected by CVE-2026-52786?
bacnet-stack: before 1.4.5; before 1.5.1; before 1.6.0.Source: cve.now feed data
Am I affected, and how do I check?
The issue is in the official apps/epics client tool in bacnet-stack v1.6.0-rc1 or earlier, not in the generic RPM ACK decoder alone. It requires the EPICS tool to have sent its legitimate ReadPropertyMultiple request for heading properties to the malicious responder. To check, identify the bacnet-stack version the epics tool was built from.Source: github.com
How do I fix CVE-2026-52786?
Upgrade to the fixed release on the matching branch: 1.4.5, 1.5.1, or 1.6.0.Source: github.com