Security readout for executives and security teams
Plain-English summary
Cloud-init could accidentally write a newly generated user password into a log file readable by local users. If an attacker already has local access to the same system, they may be able to use that logged password to access another account.
Executive priority
Treat as a focused credential-exposure issue, not a remote takeover. Prioritize shared or multi-user cloud hosts, golden images, and systems where local users are not fully trusted.
Technical view
CVE-2021-3429 is CWE-532 sensitive information exposure in cloud-init before 21.2. When configured to set a random password for a new account, cloud-init wrote that password to /var/log/cloud-init-output.log, described as world-readable. Impact is local confidentiality loss, with no source evidence of integrity or availability impact.
Likely exposure
Exposure is most likely on cloud images or hosts running cloud-init before 21.2 that used random password creation for new users. Systems not using that cloud-init behavior may not be exposed. Distro package backports need vendor-specific confirmation.
Exploitation context
The CVSS vector is local, low complexity, and requires low privileges. The bundle does not show CISA KEV listing or any cited evidence of active exploitation. The main risk is credential exposure to an already-local user.
Researcher notes
Affected metadata is sparse: the package is cloud-init and the vulnerable range is before 21.2, but distro-specific backports are not enumerated. The referenced commit is the clearest remediation artifact. Avoid assuming broader cloud platforms or exploitation beyond the provided evidence.
Mitigation direction
- Upgrade cloud-init to 21.2 or a vendor-fixed backported package.
- Apply the vendor patch or package containing the referenced Canonical commit.
- Rotate passwords for accounts created with random passwords on affected systems.
- Remove exposed secrets from readable cloud-init logs where operationally safe.
- Check vendor guidance for distro-specific fixed package versions.
Validation and detection
- Inventory cloud-init versions across images, templates, and running hosts.
- Identify systems that used cloud-init random password account creation.
- Verify fixed packages are installed or the patch is present.
- Review cloud-init output logs for exposed generated passwords.
- Confirm affected account passwords were rotated after remediation.
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-532: 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-2021-3429 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
- Medium
- CVSS
- 5.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
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 vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N1.83.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
5.5MediumVector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/canonical/cloud-init/commit/b794d426b9ab43ea9d6371477466070d86e10668CVE reference · patch
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.
Insertion of Sensitive Information into Log File
Insertion of Sensitive Information into Log File represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.