VulnerabilityPublished 13 Nov 2026

CVE-2026-100403: bacnet-stack · Uncontrolled Resource Consumption

Affects bacnet-stackSource CVE Database V5

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Not known to be exploited · CVSS 7.5 High · fixed in 1.6.1 : patch bacnet-stack soon.

Data as of 13 Nov 2026, 19:03 UTC

CVSS 3.1 base score

7.5High

How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none

CVSS scores by source
CNA (GitHub_M)	CVSS 3.1	7.5

Patch: Available – fixed in 1.6.1, 1.5.2, 1.4.6

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 13 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 13 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade bacnet-stack to 1.6.1, 1.5.2 or 1.4.6.

Affected software

Product	Affected	Fixed in
bacnet-stackbacnet-stack	Affected >=1.6.0 <1.6.1	Fixed in 1.6.1
bacnet-stackbacnet-stack	Affected >=1.5.0 <1.5.2	Fixed in 1.5.2
bacnet-stackbacnet-stack	Affected <1.4.6	Fixed in 1.4.6

AI-suggested

Apply the official patches by upgrading to bacnet-stack versions 1.4.6, 1.5.2, 1.6.1, or later. These versions include fixes that impose limits on the fragment buffer growth, preventing uncontrolled memory allocation. No other mitigation is specified or required once patched.

Description

CVE-2026-100403 is a high-severity vulnerability in the BACnet Stack open source protocol library for embedded systems. The issue affects the BACnet/SC hub's Linux WebSocket server prior to versions 1.4.6, 1.5.2, and 1.6.1. It involves uncontrolled resource consumption due to unbounded growth of a fragment buffer when processing fragmented WebSocket messages. An attacker can cause the server to repeatedly reallocate memory by sending a stream of binary continuation fragments without a final frame, potentially exhausting system memory and causing a denial of service.

Impact

Successful exploitation results in denial of service due to uncontrolled memory consumption leading to process termination or system instability. There is no impact on confidentiality or integrity reported. The CVSS v3.1 score is 7.5 (high), reflecting network attack vector, low complexity, no privileges or user interaction required, and impact limited to availability.

Summary

The BACnet Stack library versions before 1.4.6, 1.5.2, and 1.6.1 contain a resource exhaustion vulnerability (CWE-400) in the BACnet/SC hub's Linux WebSocket server. The server reassembles fragmented WebSocket messages into a per-connection buffer that grows with each non-final frame using realloc(), without any upper bound on its size. An attacker can exploit this by continuously sending binary continuation fragments without setting the FIN bit, forcing the server to allocate increasingly large buffers until memory is exhausted or the process is terminated by the operating system. This vulnerability has been patched in versions 1.4.6, 1.5.2, 1.6.1, and 1.7.0.

CWE-400Uncontrolled Resource Consumption (opens in a new tab)
Class weaknessLikelihood of exploit: High
The product does not properly control the allocation and maintenance of a limited resource.
MITRE discourages mapping vulnerabilities to this broad entry; the root cause is usually a more specific weakness.
Architecture and Design
Design throttling mechanisms into the system architecture. The best protection is to limit the amount of resources that an unauthorized user can cause to be expended. A strong authentication and access control model will help prevent such attacks from occurring in the first place.
Architecture and Design
Mitigation of resource exhaustion attacks requires that the target system either: recognizes the attack and denies that user further access for a given amount of time, or; uniformly throttles all requests in order to make it more difficult to consume resources more quickly than they can again be freed.
Architecture and Design
Ensure that protocols have specific limits of scale placed on them.
OWASP Cheat Sheets
File Upload (opens in a new tab)
OWASP ASVS 4.0.3
V12.1.1 (opens in a new tab)
Attack patterns
XML Ping of the Death (opens in a new tab)
Regular Expression Exponential Blowup (opens in a new tab)
Sustained Client Engagement (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 13 Nov 2026, 19:03 UTC

WeaknessesCWE-400

Technical details

References

Community reviews

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