CVE-2026-85058: Auth Bypass (CVSS 7.5)

Description

Moquette is a lightweight Java MQTT broker. Prior to 0.18.1, PostOffice.publishWill publishes a client-controlled Last Will message through publish2Subscribers without invoking the authorizator.canWrite check used by normal PUBLISH paths. When anonymous access is enabled and topic ACLs restrict writes, a remote client can set an ACL-protected topic as the Last Will Topic during CONNECT and perform an abnormal client disconnect, causing the broker to inject attacker-controlled messages into a topic for which the client lacks write permission. This issue is fixed in version 0.18.1.

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CVSS v3.1 Score

7.5

HIGH

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

EPSS — Exploit Prediction

0.0045

Probability of exploitation

0.37%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-862 Missing Authorization

References

Other References

https://github.com/moquette-io/moquette/commit/e23df019f6a11e22c7d2047d4f86d07095466c97 https://github.com/moquette-io/moquette/commit/f5a323fe782d1505c0097498cb22eb6ec6c96973 https://github.com/moquette-io/moquette/releases/tag/v0.18.1 https://github.com/moquette-io/moquette/security/advisories/GHSA-9jjc-fw8x-fmwx https://github.com/moquette-io/moquette/security/advisories/GHSA-9jjc-fw8x-fmwx

Frequently Asked Questions

What is CVE-2026-85058? +

Moquette is a lightweight Java MQTT broker. Prior to 0.18.1, PostOffice.publishWill publishes a client-controlled Last Will message through publish2Subscribers without invoking the authorizator.canWrite check used by normal PUBLISH paths. When anonymous access is enabled and topic ACLs restrict writes, a remote client can set an ACL-protected topic as the Last Will Topic during CONNECT and perform an abnormal client disconnect, causing the broker to inject attacker-controlled messages into a topic for which the client lacks write permission. This issue is fixed in version 0.18.1. It has a CVSS v3.1 base score of 7.5 (HIGH).

How severe is CVE-2026-85058? +

CVE-2026-85058 has a CVSS v3.1 score of 7.5 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0045, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-85058? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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