CVE
BACnet Stack unauthenticated stack overflow in Atomic-Read-File handler
Affects bacnet-stack servers that process Atomic-Read-File requests in record access mode. Fixed in 1.4.4 and 1.5.1.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- 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? →
- 0.26% · 17th 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, a BACnet open source protocol stack C library for embedded systems, contains a stack-based out-of-bounds write that a remote attacker can trigger without logging in by sending a crafted Atomic-Read-File request to the server in record access mode. The overflow corrupts memory on the stack.
Read the original description
BACnet Stack is a BACnet open source protocol stack C library for embedded systems. Prior to versions 1.4.4 and 1.5.1, there is a stack-based out-of-bounds write / stack-buffer-overflow in bacnet-stack when the server processes a malicious Atomic-Read-File request in record access mode. The bug is triggered on the real server side. A crafted request can set an excessively large RecordCount, which is later used as the loop bound for writing record data into a stack-allocated BACNET_ATOMIC_READ_FILE_DATA data structure. However, the stack object only has space for one fileData element. When the loop reaches i = 1, the code computes &data->fileData[1], which is already out of bounds, and the resulting invalid pointer is passed down to memmove(), causing a stack-buffer-overflow. 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, 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
- Severity8.2/10CVSS 8.2
- 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: 1.4.4, 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-2026-45265 (Atomic-Read-File RecordCount Stack-Based Out-of-Bounds Write in bacnet-stack), 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-2026-45265 (entry last updated 2026-11-12):
Affected:
- bacnet-stack bacnet-stack: fixed in 1.4.4; fixed in 1.5.1
Fixed versions: 1.4.4, 1.5.1.
Conditions (all must be true for the bug to be hit):
- Server processes an Atomic-Read-File request in record access mode (source: https://github.com/bacnet-stack/bacnet-stack/security/advisories/GHSA-v3gx-mwrp-xvh5)
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-2026-45265 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-45265 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-v3gx-mwrp-xvh5
- https://github.com/bacnet-stack/bacnet-stack/pull/1340
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-2026-45265
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-2026-45265"}.Timeline
- CVE published
- First seen by cve.now
Affected versions
- bacnet-stack bacnet-stack
fixed in 1.4.4; 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-2026-45265
Is CVE-2026-45265 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?
When a bacnet-stack server handles an Atomic-Read-File request in record access mode, a RecordCount value can cause it to write past the bounds of a stack buffer.Source: github.com
Which versions are affected by CVE-2026-45265?
bacnet-stack: before 1.4.4; before 1.5.1.Source: cve.now feed data
Am I affected, and how do I check?
The flaw is in bacnet-stack releases before the fixed versions 1.4.4 and 1.5.1, and only for servers that process Atomic-Read-File requests in record access mode. To check a build, look at the bacnet-stack version in use and whether the server handles Atomic-Read-File record access requests.Source: github.com
How do I fix CVE-2026-45265?
Upgrade to bacnet-stack 1.4.4 or 1.5.1, depending on which release line is in use.Source: github.com