CVE
BACnet Stack response corruption in AtomicReadFile-ACK encoder
- Exploited
- No known exploitation
- Fix
- Fixed in 1.4.4, 1.5.1
- Who is exposed
- Not reported
Do first: Upgrade to a fixed version: 1.4.4, 1.5.1.
- 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? →
- 0.27% · 19th 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? →
- 22/100 · provisional
- 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, an open source BACnet protocol library for embedded systems, has an uninitialized value flaw in the encoder that builds AtomicReadFile record-access responses. A remote attacker who does not need to log in can send a crafted AtomicReadFile request that reaches a successful record-access path, corrupting the encoded OCTET STRING length and payload boundary in network responses.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
Read the original description
BACnet Stack is a BACnet open source protocol stack C library for embedded systems. From versions 1.4.0 to before 1.4.4, and 1.5.0 to before 1.5.1, an uninitialized value use vulnerability in bacnet-stack's AtomicReadFile record-access ACK encoder allows unauthenticated remote attackers to corrupt the encoded OCTET STRING length and payload boundary in network responses by sending a crafted AtomicReadFile request that reaches a successful record-access path. This issue has been patched in versions 1.4.4 and 1.5.1.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure17/25No login or user action needed per the CVSS vector, reachable over the network without a login · Unknown: No advisory context yet
- Reach?/20Unknown. No tracked technology or package matched
- Severity5.3/10CVSS 5.3
- No patch0/5No signal
What would change the score
- Would score about 67 if added to CISA KEV
- Would score about 62 if CISA's SSVC rates exploitation active
- Would score about 27 if advisories confirm default setups are exposed
What to do
Upgrade to a fixed version: 1.4.4, 1.5.1.
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-2026-46676 (BACnet Stack: Uninitialized Value Use in AtomicReadFile-ACK Record-Access Encoder Causes Response Corruption and Conditional Information…), 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-2026-46676 (entry last updated 2026-11-12):
Affected:
- bacnet-stack bacnet-stack: from 1.4.0, fixed in 1.4.4; from 1.5.0, fixed in 1.5.1
Fixed versions: 1.4.4, 1.5.1.
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
CISA KEV: CVE-2026-46676 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-46676 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-2fwp-32cj-g3x4
- https://github.com/bacnet-stack/bacnet-stack/pull/1344
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-2026-46676
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-2026-46676"}.Timeline
- CVE published
- First seen by cve.now
Affected versions
- bacnet-stack bacnet-stack
From 1.4.0 · fixed in 1.4.4; From 1.5.0 · fixed in 1.5.1
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-2026-46676
Is CVE-2026-46676 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
Which versions are affected by CVE-2026-46676?
bacnet-stack: from 1.4.0 before 1.4.4; from 1.5.0 before 1.5.1.Source: cve.now feed data
How do I fix CVE-2026-46676?
Upgrade to a fixed version: 1.4.4, 1.5.1.Source: cve.now feed data