CVE
BACnet Stack denial of service in Timer object writeback path
Affects bacnet-stack 1.5.0 or earlier, including the default demo server, when a Timer object's writeback is configured via WriteProperty. Fixed in 1.5.1.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Exploited
- No known exploitation
- Fix
- Fixed in 1.5.1
- Who is exposed
- Default setups
Do first: Check every install: default setups are affected.
- 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? →
- 0.30% · 22nd 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? →
- 30/100 · 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? →
- Default setups
- 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
The bacnet-stack library has an uncontrolled recursion flaw in its Timer object writeback path that can overflow the stack of the default demo server. A remote attacker can reach it over the network without logging in, which causes a denial of service.
Original description
BACnet Stack is a BACnet open source protocol stack C library for embedded systems. Prior to version 1.5.1, there is a remotely reachable denial-of-service vulnerability in bacnet-stack affecting the default demo server built from the unmodified apps/server/main.c. This issue has been patched in version 1.5.1.
Who should check
Teams running bacnet-stack 1.5.0 or earlier, especially the default demo server built from apps/server/main.c, or any application with Timer objects.
“I found a remotely reachable denial-of-service vulnerability in bacnet-stack 1.5.0 affecting the default demo server built from the unmodified apps/server/main.c”
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure22/25Default setups, reachable over the network without a login
- Reach?/20Unknown. No tracked technology or package matched
- Severity7.5/10CVSS 7.5
- 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
What to do
Check every install: default setups are affected.
Upgrade to a fixed version: 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-2026-49341 (BACnet Stack: Uncontrolled recursion in Timer object writeback path leads to remote server stack 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-2026-49341 (entry last updated 2026-11-13):
Affected:
- bacnet-stack bacnet-stack: fixed in 1.5.1
Fixed versions: 1.5.1.
Conditions (all must be true for the bug to be hit):
- bacnet-stack version 1.5.0 or earlier (the advisory lists affected versions as <= 1.5.0). (source: https://github.com/bacnet-stack/bacnet-stack/security/advisories/GHSA-7r8r-2rj2-5wvr)
- A Timer object exists and its State_Change_Values and List_Of_Object_Property_References are configured via WriteProperty so the writeback targets the Timer's own Timer_Running. (source: https://github.com/bacnet-stack/bacnet-stack/security/advisories/GHSA-7r8r-2rj2-5wvr)
Setup: the bug is reachable in a default setup; no special feature or setting is needed.
Attacker needs: network access, no login, no user action.
CISA KEV: CVE-2026-49341 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-49341 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-7r8r-2rj2-5wvr
- https://github.com/bacnet-stack/bacnet-stack/pull/1347
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-2026-49341
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-2026-49341"}.Timeline
- CVE published
- First seen by cve.now
Affected versions
- bacnet-stack bacnet-stack
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-2026-49341
Is CVE-2026-49341 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?
Configuring a Timer object's state-change writeback through WriteProperty can cause uncontrolled recursion in the writeback path. This overflows the server's stack and crashes the server process, which the advisory describes as a reliable denial of service.Source: github.com
Which versions are affected by CVE-2026-49341?
bacnet-stack: before 1.5.1.Source: cve.now feed data
Am I affected, and how do I check?
The advisory lists bacnet-stack 1.5.0 and earlier as affected, including the default demo server. The setup involves a Timer object whose State_Change_Values and List_Of_Object_Property_References are set via WriteProperty so the writeback targets the Timer's own Timer_Running. Check the bacnet-stack version in use and whether a Timer object is configured this way.Source: github.com
How do I fix CVE-2026-49341?
Upgrade to bacnet-stack 1.5.1, the listed fixed version.Source: github.com