CVE-2026-95843: moquette Input Validation Flaw

Description

Moquette is a lightweight Java MQTT broker. Prior to 0.18.1, PostOffice.subscribe parses a shared-subscription filter through SharedSubscriptionUtils.extractShareName before validating the complete $share/{shareName}/{topicFilter} structure. A remote client can send a filter such as $share/grp without a topic-filter portion, causing a StringIndexOutOfBoundsException while calculating the share name. The exception terminates command handling on the shared session event loop and can deny service to other client sessions assigned to that loop. 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:N/A:H

EPSS — Exploit Prediction

0.0043

Probability of exploitation

0.36%

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-20 Improper Input Validation

Affected Products

Vendor	Product	Versions
moquette	moquette	< 0.18.1

References

Advisories & Patches

https://github.com/moquette-io/moquette/commit/affdc71fdba92dc020421678970ae70518fb6da2 https://github.com/moquette-io/moquette/pull/962 https://github.com/moquette-io/moquette/security/advisories/GHSA-5f42-97gr-vfhq https://github.com/moquette-io/moquette/security/advisories/GHSA-5f42-97gr-vfhq

Exploits

https://github.com/moquette-io/moquette/security/advisories/GHSA-5f42-97gr-vfhq https://github.com/moquette-io/moquette/security/advisories/GHSA-5f42-97gr-vfhq

Other References

https://github.com/moquette-io/moquette/releases/tag/v0.18.1

Frequently Asked Questions

What is CVE-2026-95843? +

Moquette is a lightweight Java MQTT broker. Prior to 0.18.1, PostOffice.subscribe parses a shared-subscription filter through SharedSubscriptionUtils.extractShareName before validating the complete $share/{shareName}/{topicFilter} structure. A remote client can send a filter such as $share/grp without a topic-filter portion, causing a StringIndexOutOfBoundsException while calculating the share name. The exception terminates command handling on the shared session event loop and can deny service to other client sessions assigned to that loop. 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-2026-95843? +

CVE-2026-95843 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 0.0043, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-95843? +

CVE-2026-95843 affects products from moquette, specifically: moquette. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-95843? +

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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