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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