Security readout for executives and security teams
Plain-English summary
A Mosquitto MQTT broker using a password file could accidentally accept malformed password-file entries as valid usernames without passwords. A blank line could become an empty username. This can let unauthorized clients access the broker if the vulnerable configuration and bad password-file data are present.
Executive priority
Prioritize any internet- or partner-reachable MQTT brokers on affected versions. The risk is configuration-dependent, but authentication bypass on message infrastructure can expose operational data or control flows.
Technical view
CVE-2018-12551 affects Eclipse Mosquitto 1.0 through 1.5.5 when password-file authentication is enabled. Malformed password-file data is treated as valid credentials, typically a username with no password. Password files managed only with mosquitto_passwd are stated as unaffected. Other security measures are stated as unaffected.
Likely exposure
Exposure is limited to Mosquitto 1.0-1.5.5 deployments using password-file authentication with malformed password-file content. Environments using only mosquitto_passwd to create and modify password files are reportedly unaffected.
Exploitation context
The provided sources do not show CISA KEV listing or active exploitation. Abuse requires a reachable broker, affected Mosquitto version, password-file authentication, and malformed entries already present in the password file.
Researcher notes
The key differentiator is password-file integrity, not only version. Validate exposure by combining version, authentication backend, and password-file provenance. The supplied sources do not provide CVSS, proof-of-concept status, or evidence of exploitation in the wild.
Mitigation direction
- Upgrade Mosquitto outside the affected 1.0 through 1.5.5 range.
- Apply vendor or distribution security updates, including relevant Debian packages where applicable.
- Ensure password files are created and modified only with mosquitto_passwd.
- Review password files for blank lines or malformed entries.
- Keep other broker security controls in place; sources state they are unaffected.
Validation and detection
- Inventory Mosquitto broker versions and identify any 1.0 through 1.5.5 instances.
- Confirm whether password-file authentication is enabled on each broker.
- Check password-file management process for manual edits or non-mosquitto_passwd tooling.
- Review password files for malformed records or blank lines.
- Confirm distribution security advisories were applied where package-managed.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-703: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCredential and access behavior lookup
The CVE wording references authentication or credential exposure, so valid-account and credential-access review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2018-12551 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
Source materials
- CVE List V5 sourceCVE List V5
- https://bugs.eclipse.org/bugs/show_bug.cgi?id=543401CVE reference · x_refsource_CONFIRM
- [debian-lts-announce] 20191026 [SECURITY] [DLA 1972-1] mosquitto security updateCVE reference · mailing-list, x_refsource_MLIST
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Check or Handling of Exceptional Conditions
Improper Check or Handling of Exceptional Conditions represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.