CVE-2026-8741Public exploitNetwork attack vector

Message duplication via asynchronous PacketId state commit

Published May 17, 2026 · Updated May 17, 2026

Race condition in EMQX 6.0, 6.1, and 6.2.0 allows remote authenticated users to duplicate QoS 2 messages in persistent sessions. The persistent-session handler publishes a message before asynchronously committing its PacketId, so a retransmission can publish it again. Exploitation requires durable sessions, a subscriber, and a broker crash or cross-node client reconnection during the commit window.

CVSS severity3.1
Low
EPSS probability0.28%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Race condition in EMQX 6.0, 6.1, and 6.2.0 allows remote authenticated users to duplicate QoS 2 messages in persistent sessions. The persistent-session handler publishes a message before asynchronously committing its PacketId, so a retransmission can publish it again. Exploitation requires durable sessions, a subscriber, and a broker crash or cross-node client reconnection during the commit window.

The record

CVE
CVE-2026-8741
Published
May 17, 2026
Updated
May 17, 2026
Vendor
EMQ
Product
EMQX
Classifications
CWE-362, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. May 17, 2026CVE publishedPublication date reported by the CVE source.
  2. May 17, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=6.0
  2. Affected versionversion=6.1
  3. Affected versionversion=6.2.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

EMQ · EMQXversion=6.0; version=6.1; version=6.2.0

Published CVSS scores

3.1VulDBCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L
2.1VulDBAV:N/AC:H/Au:S/C:N/I:N/A:P
1.3VulDBCVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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