How severe is CVE-2018-12543?

CVE-2018-12543 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2018-12543 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 36% (98th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2018-12543?

CVE-2018-12543 affects Eclipse Mosquitto. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2018-12543?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2018-12543 published?

CVE-2018-12543 was published on 2018-11-15 and last updated on 2026-06-17.

CVE-2018-12543

CVE-2018-12543 is a high-severity vulnerability in Eclipse Mosquitto with a CVSS 3.x base score of 7.5. Its EPSS exploit-prediction score of 36% places it in the 98th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-20.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 36% (98th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-20
Affected product: Eclipse Mosquitto
Published: 2018-11-15
Last modified: 2026-06-17

Description

In Eclipse Mosquitto versions 1.5 to 1.5.2 inclusive, if a message is published to Mosquitto that has a topic starting with $, but that is not $SYS, e.g. $test/test, then an assert is triggered that should otherwise not be reachable and Mosquitto will exit.

Frequently asked questions

What is CVE-2018-12543?: In Eclipse Mosquitto versions 1.5 to 1.5.2 inclusive, if a message is published to Mosquitto that has a topic starting with $, but that is not $SYS, e.g. $test/test, then an assert is triggered that should otherwise not be reachable and Mosquitto will exit.
How severe is CVE-2018-12543?: CVE-2018-12543 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2018-12543 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 36% (98th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2018-12543?: CVE-2018-12543 affects Eclipse Mosquitto. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2018-12543?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2018-12543 published?: CVE-2018-12543 was published on 2018-11-15 and last updated on 2026-06-17.

References

https://bugs.eclipse.org/bugs/show_bug.cgi?id=539295

Affected products (1)

cpe:2.3:a:eclipse:mosquitto:*:*:*:*:*:*:*:*

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