AWS us-east-1 DynamoDB DNS failure disrupts cloud-hosted clinical systems

Incident

AWS us-east-1 DynamoDB DNS failure disrupts cloud-hosted clinical systems

20 October 2025AWS us-east-1 (Northern Virginia); effects in USA and UKFell to tier 2: manual operationConnectivity & data Cascades

A race condition in DynamoDB's DNS automation broke a core AWS region for about 15 hours. Some cloud-hosted EHR users slowed or went to paper; others saw nothing.

Sources checked when written 26 September 2026

TierAt least 10 NHS sites using Oracle services went into downtime and reverted to paper; US Epic-on-AWS sites reported slowdowns or nothing. How tiers are assigned.

What happened

From 11:48 PM PDT on 19 October to 2:20 PM PDT on 20 October 2025, an empty DNS record for DynamoDB's regional endpoint cascaded into EC2 launch failures, load balancer errors, Lambda and container problems. Tufts Medicine, which moved Epic to AWS in 2022, reported IT slowdowns and minor delays in lab results and said clinical care was not compromised. Baptist Memorial (also Epic on AWS) and Montefiore reported no disruption. In England, a trust digital chief told Digital Health News that at least 10 NHS sites using Oracle systems went into downtime and reverted to paper; Central and North West London NHS FT confirmed it was affected. Oracle hosts some services on AWS.^[1,2,3]

Documented harm

None documented.

What it teaches

Hosting on the same cloud does not mean the same exposure; architecture and region choice decide the blast radius.
Your supplier's supplier can put you on paper.
A slowdown that delays lab results is a clinical event even if systems are 'up'.

Sources

Summary of the Amazon DynamoDB Service Disruption in the Northern Virginia (US-EAST-1) Region. Amazon Web Services, October 2025. Primary Official report · link checked 2026-09-26
AWS outage disrupts Tufts Medicine; other health systems unaffected. Becker's Hospital Review (Naomi Diaz), 21 October 2025. Secondary Journalism · link checked 2026-09-26
AWS outage causes disruption to patient care across NHS sites. Digital Health News (Jordan Sollof), 21 October 2025. Secondary Journalism · link checked 2026-09-26

All incidents · Connectivity & data · Cascades

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