Buildkite response to the eMudhra certificate compromise

What to do

• Check whether your product depends on Buildkite. Check your stack

  Paste a package.json, lockfile, Terraform or a list of domains at down.guide/stack to see every provider you depend on.

• Confirm your retries, queues and scheduled jobs caught up after the 1d it lasted.

  Anything that failed between 2026-10-20 22:13 UTC and 2026-10-21 22:38 UTC may need a replay.

• Subscribe to Buildkite's feed to hear about the next one first. RSS feed

  https://down.guide/feed?provider=buildkite works in Slack (/feed subscribe), Discord feed bots and any RSS reader.

Updates from Buildkite 4

1. investigatingOct 20, 2026, 10:13 PM UTC

   The private keys for eight certificates issued by eMudhra, an external certificate authority, have been compromised. Software that still trusts these certificates may accept fraudulent HTTPS certificates. We’re updating the services that power Buildkite and preparing new CLI and Agent releases, which we expect to ship shortly. We’re also tracking fixes to the libraries and trust stores we depend on and will apply them as they become available. We’ll update this page with the new versions and any action customers need to take. Mozilla has published background on the compromise.

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2. monitoringOct 20, 2026, 11:25 PM UTC

   We're continuing to monitor the situation, and are making releases to many of our components that run in customer infrastructure. At time of writing, we've released versions that distrust the affected eMudhra certificates for: - Buildkite agent: https://github.com/buildkite/agent: - v4.7.0: https://github.com/buildkite/agent/releases/tag/v4.7.0 - v3.138.2: https://github.com/buildkite/agent/releases/tag/v3.138.2 - Buildkite CLI: https://github.com/buildkite/cli/releases/tag/v3.64.2 - bktec: https://github.com/buildkite/test-engine-client/releases/tag/v3.3.1 We recommend updating to these versions to prevent exposure to the affected certificate providers. We will continue to issue updates for the other binaries we distribute, and are updating any internal services that are affected.

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3. monitoringOct 21, 2026, 5:07 AM UTC

   We’ve finished updating the services that power Buildkite so they no longer trust the affected eMudhra certificates. No action is needed from customers for Buildkite hosted services. For components that run in customer infrastructure, we still recommend upgrading to the releases listed in our previous update (Buildkite agent v4.7.0 / v3.138.2, Buildkite CLI v3.64.2, and bktec v3.3.1). We’re continuing to release updates for the other binaries we distribute and will post them here as they ship.

   provider

4. resolvedOct 21, 2026, 10:38 PM UTC

   All services that power Buildkite have been updated to distrust the affected certificates, and updated releases are available for the components we distribute that run in customer infrastructure: Buildkite agent: v4.7.0 and v3.138.2 Buildkite CLI: v3.64.2 bktec: v3.3.1 elastic-ci-stack-for-aws: v7.8.0 agent-stack-k8s: v0.52.0 We recommend updating to these versions to prevent exposure to the affected certificate providers.

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Corrections

None so far.

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