Summary

To improve the security posture, On September 14, 2026, Harness performed a scheduled rotation of the TLS certificate used to secure Delegate connections for accounts using mutual TLS (mTLS),The replacement
certificate passed Harness's existing pre-deployment validation and smoke testing. However, the rotation also
introduced a change in certificate authority, which required additional certificate-chain and gateway
configuration this prevented affected Delegates from connecting to Harness.
Harness has identified the contributing factors and is implementing the corrective actions described below to prevent a recurrence.

Impact

Delegates configured to use mutual TLS in Prod environment were unable to connect to Harness for
until Harness applied a temporary mitigation (disabling mTLS) that restored
connectivity while the underlying issue was corrected.

This affected the ability to run pipelines and other operations dependent on the affected Delegates. Full,
permanent connectivity — with mTLS restored to its normal, fully secure configuration — was confirmed for
both environments by 7:20 PM PST.

Root Cause

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As part of routine certificate maintenance, Harness rotated the certificate used by the gateway component that
secures mutual TLS connections for Delegates in prod environments. The rotation also introduced a
change in certificate authority, which required additional certificate-chain and gateway configuration that was
not fully covered by the existing validation process. As a result, the gateway was unable to load the new
certificate correctly, and Delegates relying on mutual TLS could not establish a secure connection.

Remediation

Once the certificate rotation was confirmed as the source of the issue, Harness engineering worked continuously
to correct the certificate and validate the fix with Citi before fully restoring the secure configuration.
Corrective and Preventive Actions

During remediation, Harness also identified and corrected a secondary issue with the replacement certificate's
chain, which required an additional deployment before connectivity was fully and permanently restored.

Next Steps

Harness is taking the following steps to prevent a recurrence of this issue:

1. Extend pre-deployment validation and smoke testing to explicitly cover certificate authority changes and full
   certificate-chain verification, closing the specific gap that allowed this configuration through.
2. Enhance automation for managing mTLS-related configuration changes,
3. Improve monitoring and alerting for Delegate connectivity, including account-level visibility, so similar issues
   are detected automatically