OpenCode disclosed a security breach on 17 October 2026, linked to a large-scale distillation attack. It affected 1.4% of OpenCode Console users, all of whom had external AI providers linked, and OpenCode emailed every affected user. If you use OpenCode Console with linked provider keys, check your inbox and rotate those keys.
What happened in the OpenCode breach?
OpenCode had a security breach linked to what it called “a large scale distillation attack”, according to OpenCode’s post on X on 17 October 2026 (UTC). The post says the breach happened the night before.
What OpenCode has confirmed so far:
| Item | What OpenCode states |
|---|---|
| Cause | A large-scale distillation attack |
| Who was affected | 1.4% of OpenCode Console users |
| Which users | Only users who had linked external AI providers to their account |
| Notification | All affected users were emailed the morning after the breach |
| Status | Ongoing; OpenCode says it can’t share more details yet |
| Response | OpenCode says Anthropic, OpenAI and Google are helping it fix the problem |
OpenCode has not said what data was taken, how the attackers got in, or how the linked provider accounts were used. CoSA Lab will update this brief when OpenCode or the AI providers publish more.
A distillation attack uses large volumes of requests to an AI model to copy its behaviour into another model. Linked provider accounts are useful to an attacker running one, because the requests are billed to someone else.
Does the OpenCode breach affect you?
Only if you use OpenCode Console and had an external AI provider linked to it. OpenCode says it emailed every affected user, and that anyone who received no email was not affected.
Check these three things:
- Search your inbox, including spam, for an email from OpenCode sent on or after 17 October 2026.
- Check whether your OpenCode Console account had any external provider linked, such as an Anthropic, OpenAI or Google key.
- If you’re on a team, ask whoever set up OpenCode Console which account it was registered to, since the email goes to that address.
What should you do this week?
If you got the email, or you aren’t sure, treat any provider key linked to OpenCode Console as exposed. The steps below are good practice for any team that stores AI provider API keys in developer tools.
- Revoke every provider key that was linked to OpenCode Console and issue new ones. Leaked OpenAI or Anthropic API credentials: what to do in the first hour walks through the order.
- Check each provider’s usage dashboard from mid-October onwards for traffic you don’t recognise. Unexpected volume is a common sign of a distillation attack running on your account.
- List every AI API key your team uses, and where each one is stored. The guide How to store AI API credentials safely covers where keys should live.
Sources
- OpenCode on X: security breach disclosure (17 October 2026)(x.com)