How severe is CVE-2018-12550?

CVE-2018-12550 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2018-12550 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (68th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2018-12550?

CVE-2018-12550 affects Eclipse Mosquitto. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2018-12550?

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-2018-12550 published?

CVE-2018-12550 was published on 2019-03-27 and last updated on 2026-06-17.

CVE-2018-12550

CVE-2018-12550 is a high-severity vulnerability in Eclipse Mosquitto with a CVSS 3.x base score of 8.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-440.

Key facts

Severity: High (CVSS 3.x base score 8.1)
CVSS v2: 6.8
EPSS exploit prediction: 1% (68th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-440
Affected product: Eclipse Mosquitto
Published: 2019-03-27
Last modified: 2026-06-17

Description

When Eclipse Mosquitto version 1.0 to 1.5.5 (inclusive) is configured to use an ACL file, and that ACL file is empty, or contains only comments or blank lines, then Mosquitto will treat this as though no ACL file has been defined and use a default allow policy. The new behaviour is to have an empty ACL file mean that all access is denied, which is not a useful configuration but is not unexpected.

Frequently asked questions

What is CVE-2018-12550?: When Eclipse Mosquitto version 1.0 to 1.5.5 (inclusive) is configured to use an ACL file, and that ACL file is empty, or contains only comments or blank lines, then Mosquitto will treat this as though no ACL file has been defined and use a default allow policy. The new behaviour is to have an empty ACL file mean that all access is denied, which is not a useful configuration but is not unexpected.
How severe is CVE-2018-12550?: CVE-2018-12550 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2018-12550 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (68th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2018-12550?: CVE-2018-12550 affects Eclipse Mosquitto. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2018-12550?: 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-2018-12550 published?: CVE-2018-12550 was published on 2019-03-27 and last updated on 2026-06-17.

References

Affected products (1)

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

More vulnerabilities in Eclipse Mosquitto

CVE-2024-10525 — Critical (CVSS 9.8): In Eclipse Mosquitto, from version 1.3.2 through 2.0.18, if a malicious broker sends a crafted SUBACK packet with no…
CVE-2018-12551 — High (CVSS 8.1): When Eclipse Mosquitto version 1.0 to 1.5.5 (inclusive) is configured to use a password file for authentication, any…
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CVE-2023-28366 — High (CVSS 7.5): 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…
CVE-2021-41039 — High (CVSS 7.5): In versions 1.6 to 2.0.11 of Eclipse Mosquitto, an MQTT v5 client connecting with a large number of user-property…

All CVEs affecting Eclipse Mosquitto →

Other CWE-440 vulnerabilities

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CVE-2025-8850 — High (CVSS 8.8): In danny-avila/librechat version 0.7.9, there is an insecure API design issue in the 2-Factor Authentication (2FA)…
CVE-2026-8806 — High (CVSS 8.7): Expected Behavior Violation vulnerability in Mitsubishi Electric MELSEC iQ-F Series FX5-ENET/IP Ethernet Module…
CVE-2023-4807 — High (CVSS 7.8): Issue summary: The POLY1305 MAC (message authentication code) implementation contains a bug that might corrupt the…
CVE-2024-30246 — High (CVSS 7.6): Tuleap is an Open Source Suite to improve management of software developments and collaboration. A malicious user could…

Browse all CWE-440 vulnerabilities →

Threat intelligence

Threat-intel indicators referencing this CVE:

175.195.238.137 (ipv4-addr)