GitHub outage on 2026-07-21: Some SSH connections using deploy keys are failing

On July 21, 2026, between 07:41 UTC and 11:57 UTC, the SSH Authentication service was degraded and some SSH connections failed to authenticate. On average, 12.2% of SSH authentication requests failed, peaking at 15.7%. Both user RSA keys and deploy keys were impacted. This was due to a change in how our SSH service handled one public-key authentication method that caused the affected authentication attempts to be rejected as invalid. <br /><br />We mitigated the incident by reverting the change, after which SSH authentication returned to normal. <br /><br />We are working to expand our automated test coverage for our SSH public-key authentication flows to catch more edge cases and to improve observability and alerting on SSH authentication failures, to reduce our time to detection and mitigation of issues like this one in the future.