Severity 0 (Critical)
Critical emergency. The system is completely unusable for a significant portion of users, or data integrity is at risk.
Critical emergency. The system is completely unusable for a significant portion of users, or data integrity is at risk.
"Everything is on Fire"
SEV0 (Severity 0) is the highest level of emergency. It means the core product is completely broken, detailed user data is being deleted, or a security breach is active.
Criteria
- Availability: Critical user flows (Login, Checkout) are failing for >10% of users.
- Data: Data corruption or loss is occurring.
- Security: Active intruder or public leak of PII.
The Response Mode
During a SEV0, normal change controls may be shortened through a documented break glass process. Move quickly, but keep an audit trail and verify that the mitigation is safer than the ongoing impact.
ExThe Black Friday Crash
“An eCommerce site went down completely at 9am on Black Friday due to traffic load.”
Why SEV0 Matters
Every second of SEV0 equals lost revenue and trust.
Requires immediate "all hands on deck" response.
May require approved "break glass" procedures to bypass normal change controls safely.