CVE
BACnet Stack out-of-bounds write in MS/TP COBS decoder
Affects bacnet-stack MS/TP deployments with COBS frame types enabled in 1.4.0 to before 1.4.6, 1.5.0 to before 1.5.1, and 1.6.0 to before 1.6.1. Fixed in 1.4.6, 1.5.1, and 1.6.1.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Exploited
- Proof of concept public, per CISA
- Fix
- Fixed in 1.4.6, 1.5.1, 1.6.1
- Who is exposed
- Not reported
Do first: Upgrade to a fixed version: 1.4.6, 1.5.1, 1.6.1.
- 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? →
- 0.36% · 30th 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? →
- 25/100 · 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? →
- Unclear
- 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
- Exploitation: poc
- Automatable: no
- Technical impact: total
Summary
BACnet Stack, a C library for embedded systems that implements the BACnet protocol, has a memory overflow in its MS/TP receive path, where a long, valid COBS-encoded payload can write past the end of the input buffer. An attacker on an adjacent network can trigger it without logging in or any user action, and the flaw is fixed in versions 1.4.6, 1.5.1, 1.6.1, and 1.7.0.
Original description
BACnet Stack is a BACnet open source protocol stack C library for embedded systems. From versions 1.4.0 to before 1.4.6, 1.5.0 to before 1.5.1, and 1.6.0 to before 1.6.1, the BACnet MS/TP receive path decodes COBS frames into an output pointer inside the same fixed input buffer, but passes the full input-buffer size as the decode capacity. A long valid COBS payload can therefore write past the end of the actual remaining buffer. This issue has been patched in versions 1.4.6, 1.5.1, 1.6.1, and 1.7.0.
Who should check
Teams running bacnet-stack MS/TP datalink deployments with COBS frame types enabled, on the affected 1.4.x through 1.5.x releases
“BACnet MS/TP datalink deployments with COBS frame types enabled”
cve.now Index
- Exploitation15/40CISA rates a proof of concept as public
- Exposure?/25Unknown. Advisories don't say whether default setups are affected
- Reach?/20Unknown. No tracked technology or package matched
- Severity9.8/10CVSS 8.8, total technical impact per CISA
- No patch0/5No signal
What would change the score
- Would score about 65 if added to CISA KEV
- Would score about 60 if CISA's SSVC rates exploitation active
- Would score about 47 if advisories confirm default setups are exposed
What to do
Upgrade to a fixed version: 1.4.6, 1.5.1, 1.6.1.
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-2026-82414 (BACnet Stack: MS/TP COBS decode overflow), 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-2026-82414 (entry last updated 2026-11-13):
Affected:
- bacnet-stack bacnet-stack: from 1.4.0, fixed in 1.4.6; from 1.5.0, fixed in 1.5.1; from 1.6.0, fixed in 1.6.1
Fixed versions: 1.4.6, 1.5.1, 1.6.1.
Conditions (all must be true for the bug to be hit):
- BACnet MS/TP datalink deployments with COBS frame types enabled (source: https://github.com/bacnet-stack/bacnet-stack/security/advisories/GHSA-8456-m9x4-j6mc)
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
Attacker needs: adjacent access, no login, no user action.
CISA KEV: CVE-2026-82414 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-82414 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-8456-m9x4-j6mc
- https://github.com/bacnet-stack/bacnet-stack/pull/1425
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-2026-82414
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-2026-82414"}.Timeline
- CVE published
- First seen by cve.now
- CISA SSVC assessment
Exploitation: poc · Automatable: no · Technical impact: total
- Record last updated
Affected versions
- bacnet-stack bacnet-stack
From 1.4.0 · fixed in 1.4.6; From 1.5.0 · fixed in 1.5.1; From 1.6.0 · fixed in 1.6.1
Evidence 4
Vendor advisory · 1
Establishes: Affected and fixed versions.
- Advisory
CVE record · 2
Establishes: The identifier and description.
- Record
- Record
Other links · 1
- Repository
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-82414
Is CVE-2026-82414 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. CISA's SSVC assessment notes a proof of concept exists. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
The MS/TP COBS decode path can write past the end of its input buffer. This corrupts heap memory. The advisory does not claim code execution.Source: github.com
Which versions are affected by CVE-2026-82414?
bacnet-stack: from 1.4.0 before 1.4.6; from 1.5.0 before 1.5.1; from 1.6.0 before 1.6.1.Source: cve.now feed data
Am I affected, and how do I check?
Versions 1.4.0 to before 1.4.6, 1.5.0 to before 1.5.1, and 1.6.0 to before 1.6.1 are in the affected ranges. The setup is a BACnet MS/TP datalink deployment with COBS frame types enabled. Check the bacnet-stack version in use and whether COBS frame types are enabled in the MS/TP configuration.Source: github.com
How do I fix CVE-2026-82414?
Upgrade to 1.4.6, 1.5.1, or 1.6.1, whichever matches the release line in use.Source: github.com