CVE-2026-82367: CWE-488 Exposure of Data Element to Wrong Session in ash-project ash_graphql

The vulnerability arises because AshGraphql.Subscription.Batcher.do_send/5 reads and deletes the resolved batch from the process dictionary under the key :batch_resolved without namespacing it by run. When do_send/5 runs inline in the publishing caller's process (in :backpressure_sync and :noproc fallbacks), a nested synchronous Ash notification can cause the inner call to reuse the outer call's :batch_resolved data. This results in records being published to the wrong subscription topic, mixing data between different actors and tenants. The fix involves saving, clearing, and restoring the :batch_resolved key around each run to isolate data per invocation.

The impact is limited to exposure of subscription data elements to incorrect sessions, potentially leaking data between different subscribers with different actors and tenants. The CVSS score is low (2.3) reflecting the network attack vector with high complexity and partial attacker privileges required. There is no indication of privilege escalation, denial of service, or remote code execution. No known exploits in the wild have been reported.

Patch status is not yet confirmed — no official fix or patch links are provided. Users should monitor the vendor advisory for updates and apply any forthcoming patches that implement the described fix of namespacing and restoring the :batch_resolved key per run. Until then, consider minimizing synchronous nested notifications or fallback modes that run do_send/5 inline if feasible.