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Fencer Intel
high 7.5

CVE-2021-41039 json

In versions 1.6 to 2.0.11 of Eclipse Mosquitto, an MQTT v5 client connecting with a large number of user-property properties could cause ex…

published 4y ago modified 4mo ago also EUVD-2021-28191

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.4%
EPSS 1.4% chance of exploitation in 30 days, percentile 71%
public exploits
0
none known

Summary

In versions 1.6 to 2.0.11 of Eclipse Mosquitto, an MQTT v5 client connecting with a large number of user-property properties could cause excessive CPU usage, leading to a loss of performance and possible denial of service.

Patch / fix

  • mosquitto Debian 14, Debian 13, Debian 12 2.0.11-1.2

debian advisories DEBIAN-CVE-2021-41039

  • mosquitto Ubuntu 22.04 LTS 2.0.11-1ubuntu1.1
  • mosquitto Ubuntu Pro 20.04 LTS 1.6.9-1ubuntu0.1~esm1

ubuntu advisories UBUNTU-CVE-2021-41039

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Is CVE-2021-41039 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-41039 updated cvss 4.3

mosquitto: DoS via malicious client

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

1.36% chance of exploitation in the next 30 days, higher than 71% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • bugs.eclipse.org https://bugs.eclipse.org/bugs/show_bug.cgi?id=575314 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P

Affected products

  • The Eclipse Foundation Eclipse Mosquitto

Classification

Weakness
  • CWE-1050 Excessive Platform Resource Consumption within a Loop

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.