CVE-2019-5432: A specifically malformed MQTT Subscribe packet crashes MQTT Brokers using the mqtt-packet module versions < 3.

Q: How do I fix CVE-2019-5432?

mqtt-packet: upgrade to 3.5.1. Exact commands for each OS are on this page.

Q: Is CVE-2019-5432 being exploited?

CVE-2019-5432 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2019-5432 affect?

CVE-2019-5432 affects mqtt-packet. Severity is high (CVSS 7.5). A specifically malformed MQTT Subscribe packet crashes MQTT Brokers using the mqtt-packet module versions < 3.5.1, 4.0.0 - 4.1.3, 5.0.0 - 5.6.1, 6.0.0 - 6.1.2 for decoding.

Q: How urgent is CVE-2019-5432?

Priority 56/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

This week

HIGH 7.5REMOTEUPGRADE

CVE-2019-5432 is a high-severity flaw (CVSS 7.5) affecting mqtt-packet. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A specifically malformed MQTT Subscribe packet crashes MQTT Brokers using the mqtt-packet module versions < 3.5.1, 4.0.0 - 4.1.3, 5.0.0 - 5.6.1, 6.0.0 - 6.1.2 for decoding.

Why this priority

High severity
Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.8% (top 22%)
CISA exploited list	No
Weakness	CWE-126, CWE-125
Published	2019-05-06
Last modified	2026-06-17

Publisher (CNA): HackerOne · Vendor: mqtt-packet project

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2019-05-06 17:29 UTCPublished CVE record published
2026-06-17 02:37 UTCUpdated Record last modified

mqtt-packet project mqtt-packet UPGRADE

Affected: < 3.5.1 · >= 4.0.0 and <= 4.1.3 · >= 5.0.0 and <= 5.6.1 · >= 6.0.0 and <= 6.1.2

Fixed in: 3.5.1

Safe to downgrade to: a release before 4.0.0

1. Check installed version

npm ls mqtt-packet

2. UPGRADE to 3.5.1

npm install mqtt-packet@">=3.5.1"

3. If no update is available yet, DOWNGRADE to a release before 4.0.0

npm view mqtt-packet versions npm install mqtt-packet@"<4.0.0"

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2019-5432?

mqtt-packet: upgrade to 3.5.1. Exact commands for each OS are on this page.

Is CVE-2019-5432 being exploited?

CVE-2019-5432 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2019-5432 affect?

CVE-2019-5432 affects mqtt-packet. Severity is high (CVSS 7.5). A specifically malformed MQTT Subscribe packet crashes MQTT Brokers using the mqtt-packet module versions < 3.5.1, 4.0.0 - 4.1.3, 5.0.0 - 5.6.1, 6.0.0 - 6.1.2 for decoding.

How urgent is CVE-2019-5432?

Priority 56/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

Related CVEs

CVE-2016-10523 HIGH 7.5 UPGRADE MQTT before 3.4.6 and 4.0.x before 4.0.5 allows specifically crafted MQTT packets to crash the application, ma

References

← Back to latest CVEs