CVE
BACnet Stack unauthenticated memory corruption in message decoder
Affects bacnet-stack 1.5.0 and earlier, including the 1.6.0-rc1 target, when the BACnet/SC datalink is in use. No vendor rating is given. Fixed in 1.4.6, 1.5.2, and 1.6.1.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:H
- Exploited
- No known exploitation
- Fix
- Fixed in 1.4.6, 1.5.2, 1.6.1
- Who is exposed
- Not reported
Do first: Upgrade to a fixed version: 1.4.6, 1.5.2, 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? →
- 0.50% · 43rd 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
Summary
BACnet Stack's BACnet/SC message decoder can be made to read one byte past a crafted message and then write decoded option data into adjacent global memory. A remote attacker needs only a single crafted frame, sent as the first message on a connection, and no login is required because the flaw is reached before authentication.
Original description
BACnet Stack is a BACnet open source protocol stack C library for embedded systems. Prior to versions 1.4.6, 1.5.2, and 1.6.1, the BACnet/SC message decoder walks the header-option list by following each option's MORE bit. Nothing rejects a list whose last option still has the MORE bit set, and the decode walk has no upper bound on how many options it processes. A single crafted BVLC-SC frame makes the walk advance one option past the end of the message and read message[message_len], one byte out of bounds. When the bytes after the message carry more MORE-set option markers, the walk keeps going: it runs past the fixed 4-entry option array and writes decoded option fields out of bounds. On the server that decode array is the static global bsc_dm, so the out-of-bounds write lands in adjacent BSS. Both faults are reachable before authentication, from the first frame a peer sends on a BACnet/SC connection, and the bytes that follow the message are the same peer's prior-frame data. This issue has been patched in versions 1.4.6, 1.5.2, 1.6.1, and 1.7.0.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure17/25No login or user action needed, reachable over the network without a login · Unknown: Advisories don't say whether default setups are affected
- Reach?/20Unknown. No tracked technology or package matched
- Severity7.7/10CVSS 7.7
- No patch0/5No signal
What would change the score
- Would score about 70 if added to CISA KEV
- Would score about 65 if CISA's SSVC rates exploitation active
- Would score about 30 if advisories confirm default setups are exposed
What to do
Upgrade to a fixed version: 1.4.6, 1.5.2, 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-2026-97692 (BACnet Stack: pre-auth out-of-bounds read that escalates to an out-of-bounds write into global memory), 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-2026-97692 (entry last updated 2026-11-13):
Affected:
- bacnet-stack bacnet-stack: fixed in 1.4.6; from 1.5.0, fixed in 1.5.2; from 1.6.0, fixed in 1.6.1
Fixed versions: 1.4.6, 1.5.2, 1.6.1.
Conditions (all must be true for the bug to be hit):
- Affected versions are bacnet-stack 1.5.0 and earlier, including the 1.6.0-rc1 target. (source: https://github.com/bacnet-stack/bacnet-stack/security/advisories/GHSA-gr74-333w-7wg8)
- The BACnet/SC datalink is in use, since the bug is in its header-option decoder. (source: https://github.com/bacnet-stack/bacnet-stack/security/advisories/GHSA-gr74-333w-7wg8)
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
Attacker needs: network access, no login, no user action.
CISA KEV: CVE-2026-97692 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-97692 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-gr74-333w-7wg8
- https://github.com/bacnet-stack/bacnet-stack/pull/1435
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-2026-97692
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-2026-97692"}.Timeline
- CVE published
- First seen by cve.now
Affected versions
- bacnet-stack bacnet-stack
fixed in 1.4.6; From 1.5.0 · fixed in 1.5.2; 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-2026-97692
Is CVE-2026-97692 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?
The BACnet/SC message decoder follows the header-option list past a fixed 4-entry option array and reads one byte out of bounds. It then writes decoded option fields past that array into adjacent global memory, and a peer can do this before authentication.Source: github.com
Which versions are affected by CVE-2026-97692?
bacnet-stack: before 1.4.6; from 1.5.0 before 1.5.2; from 1.6.0 before 1.6.1.Source: cve.now feed data
Am I affected, and how do I check?
bacnet-stack 1.5.0 and earlier are affected, including the 1.6.0-rc1 target, when the BACnet/SC datalink is in use, since the bug is in its header-option decoder. To check, look at the bacnet-stack version in use and whether the BACnet/SC datalink is configured.Source: github.com
How do I fix CVE-2026-97692?
Upgrade to the fixed release for your line: 1.4.6 for the 1.4 line, 1.5.2 for the 1.5 line, or 1.6.1 for the 1.6 line.Source: github.com