# MTLS Outage with Delegates

- Provider: [Harness](https://down.guide/harness)
- Level: confirmed
- Impact: Major outage
- lasted 8h 28m
- started 2026-09-14 19:00 UTC
- Continuous Delivery - Next Generation (CDNG), Continuous Delivery - Next Generation (CDNG), Continuous Delivery - Next Generation (CDNG)
- id: DWN-1a5a628b1d
- Official page: https://stspg.io/6mmv855y29p7

## Updates from Harness
### 2026-09-14 19:00 UTC: investigating
We are currently investigating this issue.

### 2026-09-15 00:42 UTC: identified
The issue has been identified and a fix is being implemented.

### 2026-09-15 00:45 UTC: identified
We are continuing to work on a fix for this issue.

### 2026-09-15 01:46 UTC: monitoring
A fix has been implemented and we are monitoring the results.

### 2026-09-15 03:28 UTC: resolved
This incident has been resolved.

### 2026-09-21 18:26 UTC: postmortem
# \*\*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\*\*
‌
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

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