CVE intelligence and bounded remediation
CVE-2021-23021 — F5 Nginx Controller security vulnerability
Medium
CVSS 5.5
The Nginx Controller 3.x before 3.7.0 agent configuration file /etc/controller-agent/agent.conf is world readable with current permission bits set to 644.
- Severity
- Medium
- CVSS
- 5.5 (3.1)
- Published
- 2021-06-01
- CISA KEV
- Not currently listed
- Ecosystem
- software/application
- Weaknesses
- CWE-732
Affected products
- f5 / nginx_controller
Matched remediation archetype
Privilege escalation and unsafe privilege management
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Check exposure
- Map service accounts, operating-system identities, roles, capabilities, impersonation, set-user transitions, and administrative helper paths.
- Determine whether untrusted users or lower-privilege processes can reach the affected transition or modify inputs it trusts.
- Review file, socket, registry, device, job, container, and cloud-role permissions used before and after privilege changes.
Remediate safely
- Apply the supported fix and redesign privileged operations as a minimal, authenticated, allowlisted interface.
- Drop privileges before processing untrusted input, verify the drop succeeds, and remove unnecessary roles, capabilities, and write permissions.
- Validate ownership and permissions at time of use and add explicit lower-to-higher privilege boundary tests.
Authoritative sources
Complete CVE record and remediation plan
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