CVE-2021-34431: eclipse mosquitto
Vulnerability summary
CVE-2021-34431 is a medium (CVSS 6.5) vulnerability in eclipse mosquitto. EPSS estimates a 1.11% chance of exploitation in the next 30 days, higher than 66% of scored vulnerabilities.
Not severe (CVSS 6.5, network access); no exploitation reported by the 5 checked sources
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 1 · Related 1Timeline
- 22-07-2021PublishedVulnerability first disclosed.
- 04-08-2024Last modifiedVulnerability information updated.
Description
In Eclipse Mosquitto version 1.6 to 2.0.10, if an authenticated client that had connected with MQTT v5 sent a crafted CONNECT message to the broker a memory leak would occur, which could be used to provide a DoS attack against the broker.
CVSS metrics
4 scores · 3 sources · 2 versions- OSV · UbuntuEcosystem advisory · calculated6.5MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- OSV · DebianEcosystem advisory · calculated6.5MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
EPSS trend
Probability
1.11%
Chance of exploitation in the next 30 days
Percentile
66%
Versus all other CVEs
30-day change
No change 0.00 pp
From 1.11% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Known conditions: network-reachable, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.
Debian1 product
- mosquitto< 2.0.11-1
Eclipse1 product
- mosquitto≥ 1.6, ≤ 2.0.10
The eclipse foundation1 product
- eclipse mosquitto≥ 1.6, < unspecified | ≥ unspecified, ≤ 2.0.10
Ubuntu1 product
- mosquitto< 1.6.9-1ubuntu0.1~esm1
4 vendors · 4 products
