🔴 Critical   ⏱ 5–30 min  Last verified: 20 May 2026
Affected versions: RHEL 10

📖 ~1 min read

Table of contents
  1. Symptom & Impact
  2. Environment & Reproduction
  3. Root Cause Analysis
  4. Quick Triage
  5. Step-by-Step Diagnosis
  6. Solution — Primary Fix
  7. Solution — Alternative Approaches
  8. Verification & Acceptance Criteria
  9. Rollback Plan
  10. Prevention & Hardening
  11. Related Errors & Cross-Refs
  12. References & Further Reading

Symptom & Impact

Administrators lose sudo privilege, delaying incident response and maintenance.

Environment & Reproduction

Occurs after manual edits to /etc/sudoers or invalid drop-in file syntax.

sudo -l

Root Cause Analysis

Parser error in sudoers policy files causes sudo to reject authorization checks.

Quick Triage

Use root console or recovery path and validate sudoers syntax safely.

su - ; visudo -c ; sudo journalctl -n 80 | grep -i sudo

Step-by-Step Diagnosis

Check main sudoers and /etc/sudoers.d entries for malformed lines and permissions.

visudo -c ; ls -l /etc/sudoers /etc/sudoers.d ; awk 'NF && $1 !~ /^#/' /etc/sudoers.d/*
Illustrative mockup for rhel-10 — sudoers-error-log
sudo parse error blocks privilege escalation — Illustrative mockup — Progressive Robot

Solution — Primary Fix

Repair syntax with visudo and enforce secure file permissions.

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visudo ; chmod 440 /etc/sudoers /etc/sudoers.d/* ; visudo -c
Illustrative mockup for rhel-10 — sudoers-error-fix
sudoers corrected with visudo validation — Illustrative mockup — Progressive Robot

Solution — Alternative Approaches

Boot into rescue mode to correct sudoers when no root shell is currently available.

Verification & Acceptance Criteria

sudo -l and representative privileged command succeed for approved admins.

sudo -l ; sudo systemctl status sshd

Rollback Plan

Restore last known-good sudoers backup if corrected file still fails validation.

Prevention & Hardening

Require visudo checks in CI/CD for managed sudoers templates.

May appear with PAM misconfiguration or SSSD authorization mapping failures.

Related tutorial: View the step-by-step tutorial for rhel-10.

View all rhel-10 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

sudoers manual and RHEL privileged access control best practices.

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