CVE-2026-85607

Blinko 1.8.7, a self-hosted note-taking and AI chat application, fails to verify resource ownership in several authenticated tRPC procedures (message.list, message.update, message.delete, message.clearAfter, and conversation.clearMessages), resulting in an insecure direct object reference (CWE-639). An attacker with any valid account on the instance queries these endpoints using conversation or message IDs — which are sequential integers — belonging to another user. This allows the attacker to read another user's full AI chat history, tamper with individual message contents, and delete or wipe entire conversations, causing both confidentiality and integrity loss. Only multi-user Blinko deployments are affected, since the flaw is triggered by an authenticated user of the same instance; CVSS 4.0 rates it 8.7 (High). As of now there is no public proof-of-concept, it is not in CISA's KEV catalog, and EPSS puts 30-day exploitation probability at 0.5%, so no active exploitation is known.

What to do: Update Blinko to the latest patched release as soon as the maintainers publish a fix (no fixed version number is available in the current data), and monitor the project's release notes or security advisories for the IDOR fix in the message and conversation tRPC procedures. Until patched, limit instance access to trusted accounts only, since exploitation requires authentication, and consider auditing logs for unusual cross-user access to sequential conversation/message IDs. Operators of single-user instances face minimal risk from this flaw.