HighFix available
mosquitto — security advisory
When Eclipse Mosquitto version 1.0 to 1.5.5 (inclusive) is configured to use a password file for authentication, any malformed data in the password file will be treated as valid. This typically means that the malformed data becomes a username and no password. If this occurs, clients can circumvent authentication and get access to the broker by using the malformed username. In particular, a blank line will be treated as a valid empty username. Other security measures are unaffected. Users who have only used the mosquitto_passwd utility to create and modify their password files are unaffected by this vulnerability.
- Products
- mosquitto
- Affected versions
- Not specified
- Fixed versions
- 1.4.15-r1, 1.4.15-r4, 1.5.6-r0
- CVEs
- CVE-2018-12551
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 21:57 UTC · Revision 1
Source evidence
When Eclipse Mosquitto version 1.0 to 1.5.5 (inclusive) is configured to use a password file for authentication, any malformed data in the password file will be treated as valid. This typically means that the malformed data becomes a username and no password. If this occurs, clients can circumvent authentication and get access to the broker by using the malformed username. In particular, a blank line will be treated as a valid empty username. Other security measures are unaffected. Users who have only used the mosquitto_passwd utility to create and modify their password files are unaffected by this vulnerability.
osv:ALPINE-CVE-2018-12551
mosquitto
Fixed versions: 1.5.6-r0
mosquitto
Fixed versions: 1.5.6-r0
mosquitto
Fixed versions: 1.5.6-r0
mosquitto
Fixed versions: 1.5.6-r0
mosquitto
Fixed versions: 1.5.6-r0
mosquitto
Fixed versions: 1.5.6-r0
mosquitto
Fixed versions: 1.5.6-r0
mosquitto
Fixed versions: 1.5.6-r0
mosquitto
Fixed versions: 1.5.6-r0
mosquitto
Fixed versions: 1.5.6-r0
mosquitto
Fixed versions: 1.5.6-r0
mosquitto
Fixed versions: 1.5.6-r0
mosquitto
Fixed versions: 1.5.6-r0
mosquitto
Fixed versions: 1.5.6-r0
mosquitto
Fixed versions: 1.5.6-r0
mosquitto
Fixed versions: 1.4.15-r1
mosquitto
Fixed versions: 1.4.15-r4
mosquitto
Fixed versions: 1.5.6-r0
Complete source record
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],
"modified": "2026-10-23T17:17:55.209222710Z",
"provider": "osv",
"upstream": [
"CVE-2018-12551"
],
"references": [
"https://security.alpinelinux.org/vuln/CVE-2018-12551"
]
},
"related_cves": [
{
"value": "CVE-2018-12551",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 415015,
"published_at": "2019-03-27T18:29:00.367+00:00"
}