Mosquitto
CVE-2021-28166
MEDIUM
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A10:2025 - Mishandling of Exceptional Conditions
ASVS 5.0
V16 - Security Logging and Error Handling Null pointer safety, defensive checks
MITRE ATT&CK
1 technique across 1 tactic: Impact The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Impact | CVSS score of 6.5 (MEDIUM). Attack characteristics: network attack vector, low complexity, low privileges required, no user interaction not required. |
| Exploit ScenarioDerived | A remote attacker could crash the application by dereferencing a null pointer by sending crafted requests to the affected application. |
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Alert meAnalysisAI
In Eclipse Mosquitto version 2.0.0 to 2.0.9, if an authenticated client that had connected with MQTT v5 sent a crafted CONNACK message to the broker, a NULL pointer dereference would occur. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity.
RemediationAI
A vendor patch is available. Apply the latest security update as soon as possible. Check pointers before dereferencing. Use static analysis tools to detect null pointer paths.
Affects your stack
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Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
This vulnerability is classified as NULL Pointer Dereference (CWE-476), which allows attackers to crash the application by dereferencing a null pointer. In Eclipse Mosquitto version 2.0.0 to 2.0.9, if an authenticated client that had connected with MQTT v5 sent a crafted CONNACK message to the broker, a NULL pointer dereference would occur. Affected products include: Eclipse Mosquitto. Version information: version 2.0.0.
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- Exploit and PoC references, threat intelligence from 22 sources
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Severity by source
AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
DescriptionNVD
In Eclipse Mosquitto version 2.0.0 to 2.0.9, if an authenticated client that had connected with MQTT v5 sent a crafted CONNACK message to the broker, a NULL pointer dereference would occur.
Threat Intelligence Overview
NVD
CVE.org
EPSS
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
A null pointer dereference occurs when a program attempts to access memory through a pointer that has been set to NULL (address 0x0).
Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.
Affected Products (CPE)NVD
In Eclipse Mosquitto versions 2.0.7 and earlier, the server will crash if the client tries to send a PUBLISH packet with
In versions 1.6 to 2.0.11 of Eclipse Mosquitto, an MQTT v5 client connecting with a large number of user-property proper
In Eclipse Mosquitto, from version 1.3.2 through 2.0.18, if a malicious broker sends a crafted SUBACK packet with no rea
In Mosquitto before 1.4.12, pattern based ACLs can be bypassed by clients that set their username/client id to '#' or '+
In Eclipse Mosquito, versions from 2.0.0 through 2.0.18, if a Mosquitto broker is configured to create an outgoing bridg
In Eclipse Mosquitto versions 2.0 to 2.0.11, when using the dynamic security plugin, if the ability for a client to make
In Eclipse Mosquito before and including 2.0.5, establishing a connection to the mosquitto server without sending data c
In Mosquitto before 2.0.16, a memory leak occurs when clients send v5 CONNECT packets with a will message that contains
The broker in Eclipse Mosquitto 1.3.2 through 2.x before 2.0.16 has a memory leak that can be abused remotely when a cli
Eclipse Mosquitto 1.5.x before 1.5.5 allows ACL bypass: if the option per_listener_settings was set to true, and the def
In Eclipse Mosquitto versions 1.5 to 1.5.2 inclusive, if a message is published to Mosquitto that has a topic starting w
In Eclipse Mosquitto up to version 2.0.18a, an attacker can achieve memory leaking, segmentation fault or heap-use-after
GitHub PoC
Exploit-DB